Document ID: OSHA-2011-0187-0012
Agency: osha
Document Type: Supporting & Related Material
Title: 
Posted Date: 2021-05-27T04:00Z

SUPPORTING STATEMENT FOR THE
                  INFORMATION COLLECTION REQUIREMENTS FOR THE
                     ELECTRICAL STANDARDS FOR CONSTRUCTION
                      (29 CFR PART 1926, SUBPART K) AND 
                GENERAL INDUSTRY (29 CFR PART 1910, SUBPART S)
                     OFFICE OF MANAGEMENT AND BUDGET (OMB)
                       CONTROL NO. 1218-0130 (May 2021)
	
This ICR is requesting an extension for an already approved data collection. 

A. JUSTIFICATION

 1.  Explain the circumstances that make the collection of information necessary.  Identify any legal or administrative requirements that necessitate the collection.  Attach a copy of the appropriate section of each statute and regulation mandating or authorizing the collection of information.

The main objective of the Occupational Safety and Health Act of 1970 (i.e., "the Act") is to "assure so far as possible every working man and woman in the Nation safe and healthful working conditions and to preserve our human resources" (29 U.S.C. 651).  To achieve this objective, the Act authorizes "the development and promulgation of occupational safety and health standards" (29 U.S.C. 651).

Section 6(b)(7) of the Act specifies that "[a]ny standard promulgated under this subsection shall prescribe the use of labels or other appropriate forms of warning as are necessary to insure that employees are apprised of all hazards to which they are exposed, relevant symptoms and appropriate emergency treatment, and proper conditions and precautions of safe use or exposure."  This provision goes on to state that "[t]he Secretary, in consultation with the Secretary of Health and Human Services, may by rule promulgated pursuant to section 553 of title 5, United States Code, make appropriate modifications in the foregoing requirements relating to the use of labels or other forms of warning . . . as may be warranted by experience, information, or medical or technological developments acquired subsequent to the promulgation of the relevant standard" (29 U.S.C. 655).

Under the authority granted by the Act, the Occupational Safety and Health Administration ("OSHA" or "the Agency") published the Electrical Standards for Construction (29 CFR Part 1926, Subpart K) and General Industry (29 CFR Part 1910, Subpart S); i.e., "the Standards").  The Standards address safety procedures for installation and maintenance of electric utilization equipment that prevent death and serious injuries among construction and general industry workers in the workplace caused by electrical hazards.  

 2.  Indicate how, by whom, and for what purpose the information is to be used.  Except for a new collection, indicate the actual use the Agency has made of the information received from the current collection.

The information collection provisions in these subparts require labels, markings, written programs, notifications, and tags to alert workers of the presence and the different types of electrical hazards found in the workplace, thereby, preventing serious injuries and deaths from electrocutions.

The following provisions do not contain an information collection requirement because the employer does not develop, collect, or maintain the information specified by the provisions.  Instead, the manufacturer provides the information on the equipment (i.e., it is usual and customary for employers to purchase equipment that have these markings).  Therefore, OSHA is not determining the cost or burden hours for these provisions under Item 12 of this Supporting Statement.

                                   Standard
                                  Description
                                   Subpart K
§1926.403(g) 
Marking.
§1926.405(g)(2)(ii) 

Identification, splices, and terminations-marking.
§1926.404(f)(7)(iv)(C)(6) 

Equipment connected by cord and plug.
§1926.405(j)(3)(iii)
Appliances  -  rating.
§1926.407(b)(2)(ii) 

Approved for the hazardous (classified) location  - marking.
                                   Subpart S
§1910.303(e)(1)&(2) 
Marking--Identification of manufacturer and ratings & Durability.
§1910.304(b)(2)(iv)(C)(2) 
Receptacles and cord connectors.
§1910.304(b)(2)(iv)(C)(3) 
Receptacles and cord connectors.
§1910.304(f)(1)(ix) 
Overcurrent protection -- 600 volts, nominal, or less.
§1910.304(g)(6)(vii)(B) 

Supports, enclosures, and equipment to be grounded.
§1910.305(a)(3)(ii)(A) 
Cable trays.
§1910.305(a)(3)(ii)(D) 
Cable trays.
§1910.305(g)(2)(i) 

Identification, splices, and terminations.
§1910.305(j)(3)(iii) 
Appliances.
§1910.306(h)(3)(ii)
Portable electric equipment.
§1910.306(h)(4)(iii)(B) 

Power supply circuits and receptacles for portable electric equipment.
§§1910.307(c)(2)(ii)(A), (B), (C), (D) and (E) 
Approved for the hazardous (classified) location.
§1910.307(g)(5)(ii) 
Listing and marking.
§1910.308(c)(2) 
Marking.
§1910.308(d)(2)(ii) 
Power sources.
§1910.308(d)(4) 
Identification.

The following provisions are not considered collections of information because the information is being supplied by the federal government; therefore, under 5 CFR 1320.3(c)(2), these provisions are not collections of information.

                                   Standard
                                  Description
                                   Subpart K
§1926.404(e)(1)(vi)(C) 
Overcurrent protection.
§1926.405(b)(3)(ii) 
Cabinets, boxes, and fittings.
                                   Subpart S
§1910.303(h)(5)(iii)(B) 
Working space and guarding.
§1910.304((f)(1)(viii) 

Overcurrent protection -- 600 volts, nominal, or less.
§1910.305(b)(3)(iii) 

Pull and junction boxes for systems over 600 volts, nominal.
§1910.305(c)(3)(ii)
Connection of switches.
§1910.306(c)(8) 
Warning sign for multiple disconnecting means.
§1910.306(g)(1)(iv) 
Guarding and grounding.
§1910.308(a)(5)(iv) 
Interrupting and isolating devices.
§1910.308(a)(5)(vi)(B) 
Interrupting and isolating devices.

OSHA also will use the records developed in response to these Standards to determine compliance with the safety and health provisions of the Standards.  The employer's failure to generate and disclose the information required by the Standards will affect significantly OSHA's effort to control and reduce injuries and fatalities related to electrical hazards in the workplace.

Construction--Part 1926, Subpart K

:: §1926.403--General requirements

Paragraph (h) requires legible markings on each disconnecting means for motors and appliances to indicate its purpose, unless located and arranged so the purpose is evident.  Each service, feeder, and branch circuit must have legible markings at its disconnecting means or overcurrent device to indicate its purpose, unless located and arranged so the purpose is evident.  These markings are to be of sufficient durability to withstand the environment involved.

Paragraph (i)(2)(iii) requires employers to mark entrances to rooms and other guarded locations containing exposed live parts with conspicuous warning signs forbidding unqualified persons from entering.
 
Paragraph (j)(2)(ii) requires that metal-enclosed switchgear, unit substations, transformers, pull boxes, connection boxes, and similar equipment have appropriate caution signs.

:: §1926.404--Wiring design and protection.

Paragraph (b)(1)(iii)(A) requires construction employers who implement an assured-equipment grounding-conductor (AEGC) program that covers cord sets, non-permanent receptacles, and equipment connected by a cord and plug, to have a written description of the program, including the specific procedures adopted by the employer, and to make this written program available at the job site for review and copying by OSHA compliance officers and affected employees. 

Under paragraphs (b)(1)(iii)(E), the employer must test all cord sets, receptacles that are not part of the permanent wiring of the building or structure, and cord- and plug-connected equipment that require grounding.  Employers are to perform these tests before:  first using the equipment; returning the equipment to service following repair; and using equipment after any incident that the employer reasonably suspects damaged the equipment.  In addition, an employer must conduct testing at least every three months, except for fixed cord sets and receptacles not exposed to damage, which employers must test at least every six months.

Paragraph (b)(1)(iii)(G) requires employers to record these tests, including the identity of each receptacle, cord set, and cord- and plug-in connected equipment that passed the test, and the previous testing date or interval covered by the last test.  The employer is to maintain the records using logs, color-coding, or other effective means until replaced by the next record, and make them available at the job site for inspection by OSHA compliance officers and affected employees.

Paragraph (d)(2)(ii) requires employers to post signs warning of high voltage when employees, other than qualified employees, may come in contact with energized live parts.

:: §1926.405--Wiring methods, components, and equipment for general use.

Paragraph (h) requires marking each termination enclosure with a high-voltage hazard warning.

Paragraph (j)(4)(ii)(A) requires that employers mark controller-disconnecting means for motor-branch circuits over 600 volts, nominal, and that are out of sight of the controller, with a warning label giving the location and identification of the disconnecting means that is to be locked in the open position.

Paragraph (j)(5)(ii) requires employers to indicate the operation voltage of exposed live parts of transformer installations by using warning signs or visible markings on the equipment or structure.

Paragraph (j)(6)(ii)(A) requires that capacitors rated over 600 volts, nominal, have isolating or disconnecting switches (with no interrupting rating) that interlock with the load-interrupting device or have a prominently displayed caution sign to prevent switching load current.

:: §1926.408--Special systems.

Paragraph (a)(2)(iii) requires that isolating means not designed to interrupt the load current of the circuit either be interlocked with an approved circuit interrupter or provided with a sign warning against opening them under load.

Paragraph (a)(3)(i) requires that a metallic enclosure provided on the mobile machine for enclosing the terminals of the power cable must have provision for locking so only authorized qualified persons may open it, and it must have a sign warning of the presence of energized parts.

Paragraph (a)(3)(ii) requires employers to enclose energized switching and control parts in effectively grounded and locked metal cabinets or enclosures that are accessible only to authorized qualified persons, and that have a sign warning of the presence of energized parts.

:: §1926.416--General requirements.

Paragraph (a)(3) requires warning signs to alert employees to the presence of energized electric power circuits, and to advise them of the location of such lines, the hazards involved, and what protective measures to take.

:: §1926.417--Lockout and tagging of circuits.

Paragraphs (a), (b), and (c) require employers to tag deactivated controls to energized or deenergized circuits and equipment while employees are working on them.  In addition, employers are to render deenergized equipment and circuits inoperative, and attach tags at points that control the release of energy to the deenergized circuits and equipment.  These tags must plainly identify these circuits and equipment.

General Industry-- Part 1910, Subpart S 

:: §1910.303--General requirements.

Paragraphs (f)(1) & (2) require legible markings on each disconnecting means for motors and appliances to indicate its purpose, unless located and arranged so the purpose is evident.  Each service, feeder, and branch circuit, at its disconnecting means or overcurrent device, must have legible markings to indicate its purpose, unless located and arranged so the purpose is evident.  These markings are to be of sufficient durability to withstand the environment involved.

Paragraph (f)(5)(i) and (ii) of this section requires the employer to mark in the indicated field the circuit breakers' and fuses' series combination ratings of the equipment given by the manufacturer.  The wording shall state "Caution - Series Combination System Rated ____  Amperes Identified Replacement Component Required."  The employer has to legibly mark on the blank that rating. 

Paragraph (g)(2)(iii) requires employers to mark entrances to rooms and other guarded locations containing exposed live parts with conspicuous warning signs forbidding unqualified persons to enter.

Paragraph (h)(2)(iii)(B) (previously §1910.303(h)(2)(ii)) requires that metal-enclosed switchgear, unit substations, transformers, pull boxes, connection boxes, and similar equipment have appropriate caution signs. 

:: §1910.304--Wiring design and protection.

Paragraph (b)(1) of this section requires the employer to identify the phase and system of each ungrounded conductor of a multiwire branch circuit in a building containing more than one nominal voltage system.  This marking is required to be permanently posted on each panelboard. 

Paragraph (b)(3)(ii)(C)(1) requires a written description of the [assured equipment grounding conductor (AEGC)] program, including the specific procedures adopted by the employer, shall be available at the jobsite for inspection and copying by the Assistant Secretary of Labor and any affected employee[.]

Paragraph (b)(3)(ii)(C)(6) requires tests performed as required in paragraph (b)(3)(ii)(C) of this section shall be recorded.  This test record shall identify each receptacle, cord set, and cord-and plug-connected equipment that passed the test and shall indicate the last date it was tested or the interval for which it was tested.  This record shall be kept by means of logs, color coding, or other effective means and shall be maintained until replaced by a more current record.  The record shall be made available on the jobsite for inspection by the Assistant Secretary and any affected employee.

Paragraph (e)(2)(ii) (previously §1910.304(d)(2)(ii)) requires employers to post signs warning of high voltage when employees, other than qualified employees, may come in contact with energized live parts.

:: §1910.305--Wiring methods, components, and equipment for general use.

Paragraph (h)(8) requires marking each termination enclosure with a high-voltage hazard warning.

Paragraph (j)(4)(ii) requires that employers mark controller-disconnecting means for motor-branch circuits over 600 volts, nominal, and that are out of sight of the controller, with a warning label giving the location and identification of the disconnecting means that is to be locked in the open position.

Paragraph (j)(5)(ii) requires that employers indicate the operating voltage of exposed live parts of transformer installations by using warning signs or visible markings on the equipment or structure.

Paragraph (j)(6)(ii)(C) (previously §1910.305(j)(6)(ii)(A)) requires that capacitors rated over 600 volts, nominal, have isolating or disconnecting switches (with no interrupting rating) that interlock with the load interrupting device or have a prominently displayed caution sign to prevent switching load current.

:: §1910.306--Specific purpose equipment and installations.   

Paragraph (c)(6)(i) requires the employer to identify the disconnecting means with the number that corresponds to the driving machine number that it controls where there is more than one driving machine in the machine room.

Paragraph (c)(6)(ii) requires the employer to provide the disconnecting means with a sign to identify the location of the supply side overcurrent protective device. 

Paragraph (k)(4)(iv)(B) requires the employer to list single-pole separable connectors used in portable professional motion picture and television equipment and to mark the system to which they are connected.

:: §1910.307--Hazardous (classified) locations. 

Paragraph (b) requires that the employer document all areas designated as hazardous (classified) locations.  This documentation shall be available to those authorized to design, install, inspect, maintain, or operate electric equipment at the location. 
 
:: §1910.308--Special systems.

Paragraph (a)(5)(vii) (previously §1910.308(a)(2)(iii)) requires a means (for example, a fuseholder and fuse designed for the purpose) shall be provided to completely isolate equipment for inspection and repairs.  Isolating means that are not designed to interrupt the load current of the circuit shall be either interlocked with an approved circuit interrupter or provided with a sign warning against opening them under load.

Paragraph (a)(6)(i) (previously §1910.308(a)(3)(i)) requires that a metallic enclosure provided on the mobile machine for enclosing the terminals of the power cable must have provisions for locking so only authorized qualified persons may open it, and it must have a sign warning of the presence of energized parts.

Paragraph (a)(6)(ii) (previously §1910.308(a)(3)(ii)) requires employers to enclose energized switching and control parts in effectively grounded and locked metal cabinets or enclosures that are accessible only to authorized qualified persons, and be marked with a sign warning of the presence of energized parts. 

Paragraph (b)(3)(i) requires the employer to place a sign at the service entrance equipment indicating the type and location of on-site emergency power sources.  A sign is not required for individual unit equipment.

Paragraph (b)(3)(ii) requires a sign at the grounding location that identify all emergency and normal sources connected at the location.

:: §1910.333--Selection and use of work practices.

Paragraph 1910.333(b)(2)(i) requires employers to maintain a written copy of the procedure outlined in paragraph (b)(2) of this standard, and to make it available for inspection by employees and by the Assistant Secretary of Labor and his/her authorized representatives.  The written procedures may be a copy of paragraph (b) of this standard.

Paragraph 1910.333(b)(2)(iii)(B) requires employers to ensure that each tag used contains a statement prohibiting unauthorized operation of the disconnecting means and removal of the tag.

Paragraph 1910.333(b)(2)(v)(B) requires employers to warn employees exposed to the hazards associated with reenergizing the circuit or equipment to stay clear of the circuits and equipment.

 3.  Describe whether, and to what extent, the collection of information involves the use of automated, electronic, mechanical, or other technological collection techniques or other forms of information technology, e.g., permitting electronic submission of responses, and the basis for the decision for adopting this means of collection.  Also describe any consideration of using information technology to reduce burden.

Employers may use automated, electronic, mechanical, or other technological information collection techniques, or other forms of information technology (e.g., electronic submission of responses) when establishing and maintaining the required records.  The Agency wrote the paperwork requirements of the Standards in performance-oriented language (i.e., in terms of what data to collect, not how to record the data).

4.  Describe efforts to identify duplication.  Show specifically why any similar information already available cannot be used or modified for use for the purpose(s) described in A.2. above.

Some local jurisdictions enforce the National Electrical Code (NEC), which has information collection requirements similar to the requirements specified by the Standards.  However, OSHA has insufficient data from which to estimate the level of duplication.

Every edition of the NEC from the 1984 edition to the 2017 edition (representing eleven code cycles) requires that specific AEGC tests be conducted, recorded, and made available to the authority having jurisdiction.  However, the specific authority having jurisdiction varies from state to state.

 5.  If the collection of information impacts small businesses or other small entities, describe the methods used to reduce the burden.

The information collection requirements specified by the Standards do not have a significant impact on a substantial number of small entities.  The Standards use performance language whenever possible to provide compliance flexibility to employers and to reduce the impact on small businesses.  Performance language may require small business employers to rely more often than other employers on contractors to provide the safety and health technical expertise necessary to comply with these requirements.

 6.  Describe the consequence to Federal program or policy activities if the collection is or is not conducted less frequently, and any technical or legal obstacles to reducing the burden.

The Agency believes that the information collection frequencies required by the Standards are the minimum frequencies necessary to effectively monitor employee exposure to electrical hazards in construction and general industries, and thereby to fulfill its mandate "to assure so far as possible every working man and woman in the Nation safe and healthful working conditions and to preserve our human resources" as specified by the Act at 29 U.S.C. 651.

 7.  Explain any special circumstances that would cause an information collection to be conducted in a manner:

 Requiring respondents to report information to the agency more often than quarterly;
      
 Requiring respondents to prepare a written response to a collection of information in fewer than 30 days after receipt of it;

 Requiring respondents to submit more than an original and two copies of any document;

 Requiring respondents to retain records, other than health, medical, government contract, grant-in-aid, or tax records for more than three years;

 In connection with a statistical survey that is not designed to produce valid and reliable results that can be generalized to the universe of study;

 Requiring the use of statistical data classification that has not been reviewed and approved by OMB;

 That includes a pledge of confidentially that is not supported by authority established in statue or regulation that is not supported by disclosure and data security policies that are consistent with the pledge, or which unnecessarily impedes sharing of data with other agencies for compatible confidential use; or

 Requiring respondents to submit proprietary trade secret, or other confidential information unless the agency can prove that it has instituted procedures to protect the information's confidentially to the extent permitted by law.

No special circumstances exist that require employers to collect information using the procedures specified by this item.  The requirements are within the guidelines set forth in 5 CFR 1320.5.

 8.  If applicable, provide a copy and identify the date and page number of publication in the Federal Register of the agency's notice, required by 5 CFR 1320.8(d), soliciting comments on the information collection before submission to OMB.  Summarize public comments received in response to that notice and describe actions taken by the agency in response to those comments specifically address comments received on cost and hour burdens.
      
Describe efforts to consult with persons outside the agency to obtain their views on the availability of data, frequency of collection, the clarity of instructions and recordkeeping, disclosure, or reporting format (if any), and on the data elements to be recorded, revealed, or reported.

Consultation with representatives of those from whom information is to be obtained or those who must compile records should occur at least once every three years -- even if the collection of information activity is the same as in prior periods.  There may be circumstances that mitigate against consultation in a specific situation.  These circumstances should be explained.
As required by the Paperwork Reduction Act of 1995 (44 U.S.C. 3506(c)(2)(A)), OSHA published a notice in the Federal Register on May 13, 2021 (86 FR 262337)  requesting public comments on its proposed extension of the information collection requirements contained in the Electrical Standards for Construction (29 CFR Part 1926, Subpart K) and General Industry (29 CFR Part 1910, Subpart S) (Docket number OSHA-2011-0187).  This notice was part of a preclearance consultation program intended to provide those interested parties the opportunity to comment on OSHA's request for an extension by the Office of Management and Budget (OMB) of a previous approval of the information collection requirements found in the above Standards. The agency will respond to any comments received in response to this notice.
9.  Explain any decision to provide any payments or gift to respondents, other than remuneration of contractors or grantees.
The Agency will not provide payments or gifts to the respondents.

10.  Describe any assurance of confidentiality provided to respondents and the basis for the assurance in statute, regulation, or agency policy.

The paperwork requirements specified by these Standards do not involve confidential information.

11.  Provide additional justification for any questions of a sensitive nature, such as sexual behavior and attitudes, religious beliefs, and other matters that are commonly considered private.  This justification should include the reasons why the agency considers the questions necessary, the specific uses to be made of the information, the explanation to be given to persons from whom the information is requested, and any steps to be taken to obtain their consent.

None of the provisions in the Standards require sensitive information.
 
12.  Provide estimates of the hour burden of the collection of information.  The statement should: 

 Indicate the number of respondents, frequency of response, annual hour burden, and an explanation of how the burden was estimated.  Unless directed to do so, agencies should not conduct special surveys to obtain information on which to base hour burden estimates.  Consultation with a sample (fewer than 10) of potential respondents is desirable.  If the hour burden on respondents is expected to vary widely because of differences in activity, size, or complexity, show the range of estimated hour burden, and explain the reasons for the variance.  Generally, estimates should not include burden hours for customary and usual business practices.

 If this request for approval covers more than one form, provide separate hour burden estimates for each form.

 Provide estimates of annualized cost to respondents for the hour burdens for collections of information, identifying and using appropriate wage-rate categories.

Respondent Burden Hour and Cost Burden Determinations 

Estimating the Wage Rates

OSHA determined the wage rates from Occupational Employment Statistics, National Occupational Employment and Wages, May 2020, Bureau of Labor Statistics, U.S. Department of Labor, and  the  fringe benefits of 31.3 percent from the Thursday, March 18, 2021 News Release, Employer Costs for Employee Compensation  -  December 2020, (percent for Standard Occupational Classifications (SOCs) 17-2071 (electrical certified engineer), 17-3023 (electrical and electronic engineering technician), and 11-9041 (engineering manager).  The mean hourly wages for these classifications are $50.96 (electrical certified engineer), $32.84 (electrical and electronic engineering technician), and $76.01 (engineering manager) before fringe benefits.

The costs of labor used in this analysis are, therefore, estimates of the total hourly compensation rate. These hourly wages are:

             Table 1--- Estimated Wage Rates with Fringe Benefits

Occupation
SOC
Mean hourly rates [a]
Fringe benefit
[b]
Wage rates   
[c=(a/1-b)]
Engineering Manager
11-9041
$76.01
0.313

$110.64

Electrical Certified Engineer
17-2071
$50.96
0.313

$74.18

Electrical and Electronic Engineering Technician (EEET)
17-3023
$32.84
0.313

$47.80

Estimating Cost and Burden Hours

The following sections are the burden hour and cost determinations for the information collection requirements specified by the Standards.  The data is based on the final economic analysis (FEA) prepared during the revision of the final rule for 29 CFR Part 1910, Subpart S, as well as OSHA's estimate of the time it would take an employee to perform the necessary electrical safety procedures.

Estimating the Number of Establishments and Employees

Construction Industries: (NAICS 236,238)

There are 677,718 establishments with 5,579,177 employees in the construction industry according to the 2017 --  County Business Patterns. At an average of 9 jobsites per establishment, OSHA estimates that there are 6,099,462 jobsites affected in the construction industry. (677,718 affected establishments x 9 jobsites = 6,099,462 jobsites).

Burden-Hour and Cost Determinations

 §1926.403(h); 1910.303(f)(1)&(2)--Identification of disconnecting means and circuits.

98The burden for this requirement applies solely to employers in the construction industry because the task occurs only during initial installation of motors and appliances.  The only burden for general industry is checking that the task has been done. The Agency assumes that only 1% of the jobsites will need to mark and identify their system (1% of 6,099,462 jobsites = 60,994.62). OSHA estimates that it takes an EEET five minutes (5/60 hr.) to mark an average 30 disconnecting means or overcurrent devices usually found on a single panel board at a jobsite.

	Burden hours:  60,994.62 jobsites x 5/60 hour = 5,082.89 hours
                Cost:  5,082.89 hours x $47.80 = $242,962.14

 §1926.403(i)(2)(iii); 1910.303(g)(2)(iii)

Guarding of live parts (iii) Entrances to rooms and other guarded locations containing exposed live parts shall be marked with conspicuous warning signs forbidding unqualified persons to enter. The only burden for general industry is checking that the task has been done.

OSHA believes that it is usual and customary practice for employers to use the warning signs repeatedly.  These signs can be used from one location to another which reduces the burden of constructing or ordering the sign.  These reusable warning signs reduce cost of acquiring a new sign on the employer.

OSHA estimates that it will take 3 minutes (.05 hour) to post a warning sign.  Only 5% of the jobsites will need to post new signs = 6,099,462 jobsites x .05 = 304,973.1

	    	Burden hours:   304,973.1 jobsites x 1 sign x .05 hour = 15,248.66 hours
			    Cost:   15,248.66 hours x $47.80 = $728,885.95

 §1926.403(j)(2)(ii); 1910.303(h)(2)(iii)(B)

Installations accessible to unqualified persons (ii) Electrical installations that are open to unqualified persons shall be made with metal-enclosed equipment or shall be enclosed in a vault or in an area, access to which is controlled by a lock. If metal-enclosed equipment is installed so that the bottom of the enclosure is less than 8 feet above the floor, the door or cover shall be kept locked.  Metal-enclosed switchgear, unit substations, transformers, pull boxes, connection boxes, and other similar associated equipment shall be marked with appropriate caution signs.  If equipment is exposed to physical damage form vehicular traffic, suitable guards shall be provided to prevent such damage.  Ventilating or similar openings will be deflected from energized parts.

The caution signs are posted at the time the equipment is installed and therefore this requirement is only done one time.  The burden is taken in construction. The only burden for general industry is checking that the task has been done.

OSHA estimates that it will take 3 minutes (.05 hour) to post the signs.  Only 10% of the jobsites will be affected (6,099,462 jobsites x .10 = 609,946.2).

	   	    Burden hours:   609,946.2 jobsites x 1 sign x .05 hour = 30,497.31 hours
			        Cost:   30,497.31 hours x $47.80 = $1,457,771.42

 § 1926.404(b)(1)(iii)--Assured equipment grounding conductor (AEGC) program.
   
Regarding paragraph (b)(1)(iii)(A), OSHA estimates that 99% (6,080,095) of the construction sites elect to use ground-fault circuit interrupters and the remaining 1% (60,994.62) jobsites will use the AEGC program.  OSHA estimates that it takes one hour (1.00 hr.) for an EEET to develop an AEGC program.  Accordingly, the Agency estimates that the total annual burden hours and cost of developing the written AEGC programs are:

	Burden hours:  60,994.62 jobsites x 1 hour = 60,994.62 hours 
		           Cost:  60,994.62 hours x $47.80 = $2,915,542.84

 §1926.404(d)(2)(ii); §1910.304(e)(2)(ii)

(d)(2) Services over 600 volts nominal. (ii) Warning signs.  Signs warning of high voltage shall be posted where other than qualified employees might come in contact with live parts.
The only burden for general industry is checking that the task has been done.

OSHA believes that it is usual and customary practice for employers to use the warning signs repeatedly.  These signs can be used from one location to another which reduces the cost of acquiring a new sign on the employer.

OSHA estimates that it will take three minutes (.05 hour) to post the warning sign.  Only 3% of the jobsites (182,983.86) will need to post new signs.

	    	Burden hours:   182,983.86 jobsites x 1 sign x .05 hour = 9,149.19 hours
			    Cost:   9,149.19 hours x $47.80 = $437,331.28

 §1926.405(h); §1910.305(h)(8) 

Terminations (h):  This paragraph applies to portable cables used at more than 600 volts nominal. Termination enclosures shall be suitably marked with a high voltage hazard warning, and terminations shall be accessible only to authorized and qualified employees.

The caution signs are posted at the time the equipment is installed. This requirement is done only one time and; therefore, the burden is taken in construction. The only burden for general industry is checking that the task has been done.

OSHA 	estimates that it will take 3 minutes (.05 hour) to post the new sign.  And only 5% of the jobsites (304,973.1) will be affected.

	                 	Burden hours:    304,973.1 jobsites x 1 sign x .05 hour = 15,248.66 hours
			    Cost:    15,248.66 hours x $47.80 = $728,885.95

 §1926.405(j)(4)(ii)(A); §1910.305(j)(4)(ii)-- Motors.

Disconnecting means (j)(4)(ii):  An individual disconnecting means shall be provided for each controller. A disconnecting means shall be located within sight of the controller location. However, a single disconnecting means may be located adjacent to a group of coordinated controllers mounted adjacent to each other on a multi-motor continuous process machine. The controller disconnecting means for motor branch circuits over 600 volts, nominal, may be out of sight of the controller, if the  controller is marked with a warning label giving the location and identification of the disconnecting means that is to be locked in the open position.

 The burden for this task applies solely to employers in the construction industry because the task occurs only during initial installation of controller-disconnecting means.  The only burden for general industry is checking that the task has been done.

OSHA estimates that it takes five minutes (5/60 hour) for an EEET to construct and post a warning label for each controller-disconnecting means, and that 2% of the new construction sites (121,989.24) use these warning labels on a single controller-disconnecting means.

	Burden hours:  121,989.24 jobsites x 5/60 hour = 10,165.77 hours
		    Cost:  10,165.77 hours x $47.80 = $485,923.81

§1926.405(j)(5)(ii); §1910.305(j)(5)(ii) -- Equipment for general use.

Transformer (j)(5)(ii):  The operating voltage of exposed live parts of transformer installations shall be indicated by signs or visible markings on the equipment or structure. The only burden for general industry is checking that the task has been done.

The burden for this task applies solely to employers in the construction industry because the task occurs only during initial installation.  OSHA estimates that it takes three minutes (.05 hour) for an EEET to post a warning sign, and that 5% of the construction sites (304,973.1) need to use warning signs.

	Burden hours:  304,973.1 jobsites x .05 hour = 15,248.66 hours
                            Cost:  15,248.66 hours x $47.80 = $728,885.95
	
 §1926.405(j)(6)(ii)(A); §1910.305(j)(6)(ii)(C) -- Equipment for general use.

Capacitors (j)(6)(ii):  Isolating or disconnecting switches (with no interrupting rating) shall be interlocked with the load interrupting device or shall be provided with prominently displayed caution signs to prevent switching load current; and only the burden for general industry is checking that the task has been done.

OSHA estimates that it will take 3 minutes (.05 hour) to post the signs.  Only 2% of the jobsites (121,989.24) will be affected.

	   	    Burden hours:   121,989.24 jobsites x 1 sign x .05 hour = 6,099.46 hours
			        Cost:    6,099.46 hours x $47.80 = $291,554.19

 §1926.408(a)(2)(iii); 1910.305(a)(5)(vii) -- Special Systems

Interrupting and isolating devices (a)(2)(iii) A means (for example, a fuseholder and fuse designed for the purpose) shall be provided to completely isolate equipment for inspection and repairs. Isolating means that are not designed to interrupt the load current of the circuit shall be either interlocked with an approved circuit interrupter or provided with a sign warning against opening them under load. The only burden for general industry is checking that the task has been done.

OSHA estimates that it will take 3 minutes (.05 hour) to post the warning sign. Only 1% of the jobsites will need to post new signs = 6,099,462 jobsites x .01 = 60,994.62

	    	Burden hours:   60,994.62 jobsites x 1 sign .05 hour = 3,049.73 hours
			    Cost:    3,049.73 hours x $47.80 = $145,777.09

 §1926.408(a)(3)(i); 1910.305(a)(6)(i) -- Special Systems

Mobile and portable equipment (a)(3)(i) A metallic enclosure shall be provided on the mobile machine for enclosing the terminals of the power cable. The enclosure shall include provisions for a solid connection for the grounding terminal to effectively ground the machine frame. The method of cable termination used shall prevent any strain or pull on the cable from stressing the electrical connections.  The enclosure shall have provision for locking so only authorized qualified persons may open it and shall be marked with a sign warning of the presence of energized parts.

OSHA believes that it is a usual and customary practice for employers to use the warning signs repeatedly.  These signs can be used from one location to another which reduces the cost of acquiring a new sign on the employer.

OSHA estimates that it will take 3 minutes (.05 hour) to acquire and post the warning sign.  Only 2% of the jobsites (121,989.24) will need to post new signs.

	    	Burden hours:   121,989.24 jobsites x 1 sign x .05 hour = 6099.46 hours
			    Cost:    6099.46 hours x $47.80 = $291,554.19

 §1926.408(a)(3)(ii); §1910.305(a)(6)(ii) --  Special Systems

Mobile and portable equipment--(a)(3)(ii): All energized switching and control parts shall be enclosed in effectively grounded metal cabinets or enclosures.  Circuit breakers and protective equipment shall have the operating means projecting through the metal cabinet or enclosure so these units can be reset without locked doors being opened.  Enclosures and metal cabinets shall be locked so that only authorized qualified persons have access and shall be marked with a sign warning of the presence of energized parts.  Collector ring assemblies on revolving-type machines (shovels, draglines, etc.) shall be guarded.

OSHA believes that it is a usual and customary practice for employers to use the warning signs repeatedly.  These reusable warning signs reduce the cost of a new sign on the employer.

OSHA estimates that it will take 3 minutes (.05 hour) to acquire and post the warning sign.  Only 2% of the jobsites (121,989.24) will need to post new signs.

	    	Burden hours:   121,989.24 jobsites x 1 sign x .05 hour = 6099.46 hours
			    Cost:    6099.46 hours x $47.80 = $291,554.19

 §1926.416(a)(3) -- General requirements

Before work is begun, the employer shall ascertain by inquiry or direct observation, or by instruments, whether any part of an energized electric power circuit, exposed or concealed, is so located that the performance of the work may bring any person, tool, or machine into physical or electrical contact with the electric power circuit. The employer shall post and maintain proper warning signs where such a circuit exists. The employer shall advise employees of the location of such lines, the hazards involved, and the protective measures to be taken.

These warning signs and marks alert unqualified and unauthorized employees of the presence of electrical hazards, and notify electricians of the need to exercise caution and to take other measures to protect themselves when they are near electrical hazards. 

OSHA estimates that it will take 3 minutes (.05 hour) to acquire and post the warning sign.  Only 2% of the jobsites (121,989.24) will need to use new signs.

	    	Burden hours:   121,989.24 jobsites x 1 sign x .05 hour = 6099.46 hours
			    Cost:    6099.46 hours x $47.80 = $291,554.19

 §1926.417(a), (b), & (c)--Lockout and tagging of circuits
Controls:  (a) Controls that are to be deactivated during the course of work on energized or deenergized equipment or circuits shall be tagged. 
Equipment and circuits:  (b) Equipment or circuits that are deenergized shall be rendered inoperative and shall have tags attached at all points where such equipment or circuits can be energized.
Tags:  (c) Tags shall be placed to identify plainly the equipment or circuits being worked on.
The Agency assumes that contractors tag one electrical hazard at each jobsite, and that an electrician spends one minute (.02 hour) tagging each hazard.  OSHA estimates that only 5% of the jobsites (304,973.1) will need to use lockout and tagging.
		Burden hours:   304,973.1 jobsites x 1 tag x .02 hour = 6099.46 hours
			    Cost:   6099.46 hours x $47.80 = $291,554.19 

General Industry:

Following the industries covered by Subpart S outlined in the Final Economic Analysis (FEA) (72 FR 7136) of the final rule to revise 29 CFR Part 1910, there are now 500,876 establishments and 5,205,215 employees in under NAICS codes 237 and 238 according the 2017 -- 2012 County Business Patterns.  OSHA estimates that there are 51% of the establishments in general industry under state and local governments already covered under the latest National Electric Code (NEC) meeting the Standard and the other 49% employer are not governed by state and local governments.  Based on the analysis of the remaining employers (i.e., those employers not governed by states and cities mandating the NEC), OSHA estimates that a total of 245,429.24 establishments and 2,550,555.35 employees affected by the Standards.

Based on the total number of affected establishments in general industry, only the new installations will be affected by this requirement.  OSHA estimates that only 1% of the affected establishments will be new (i.e., 245,429.24 establishments x 1% = 2,454.29 new establishments).  

 §1910.303(f) -- Disconnecting means and circuits 

Paragraph (f)(5)(i)--Where circuit breakers or fuses are applied in compliance with the series combination ratings marked on the equipment by the manufacturer, the equipment enclosures shall be legibly marked in the field to indicate that the equipment has been applied with a series combination rating.

Paragraph (f)(5)(ii)--The marking required by paragraph (f)(5)(i) of this section shall be readily visible and shall state "Caution -- Series Combination System Rated_____Amperes. Identified Replacement Component Required."

Since this information is readily available to employers (i.e., provided on the equipment by the manufactures), OSHA estimates that an EEET takes two minutes (.03 hour) to determine the series-combination ratings on the equipment and mark the ampere rating of the system in the designated space.  In addition, the Agency estimates that 75% (1,840.72) of the new establishments need to mark the ampere ratings (2,454.29 new establishments x .75 = 1,840.72 new establishments), and that each new establishment needs to mark one equipment enclosure.  Accordingly, the total yearly burden hour and cost estimates resulting from this requirement are:
      
      Burden hours:	 1,840.72 new installations x .03 hour = 55.22 hours
		            Cost:  55.22 hours x $47.80 = $2,639.52

 §1910.304(b) -- Branch circuits

Identification of multiwire branch circuits (b)(1)--Where more than one nominal voltage system exists in a building containing multiwire branch circuits, each ungrounded conductor of a multiwire branch circuit, where accessible, shall be identified by phase and system. The means of identification shall be permanently posted at each branch-circuit panelboard.

Since this information is readily available to employers (i.e., provided on the equipment by the manufacturer), OSHA estimates that it takes an EEET approximately one minute (.02 hour) to mark the phase and system of each ungrounded conductor.  The Agency also estimates that 75% (1,840.72) of the new establishments need to perform this task (i.e., mark one ungrounded conductor).  Thus, the total annual burden hours and cost estimated for this requirement are:

      Burden hours:	 1,840.72 new establishments x .02 hour = 36.81 hours
                   Cost:	 36.81 hours x $47.80 = $1,759.52

Ground-fault circuit interrupter protection for personnel (b)(3)(ii)(C)(1)--A written description of the program, including the specific procedures adopted by the employer, shall be available at the jobsite for inspection and copying by the Assistant Secretary of Labor and any affected employee;

Assuming that 99.97% of the establishments will use ground-fault circuit-interrupter protection and; therefore, are not eligible to use an AEGC program, then the Agency estimates that .03% (73.63) of the establishments will use a written AEGC program (245,429.24 establishments x .0003 = 73.63 establishments).  Based on information obtained from construction-trade associations, employers are provided with preprinted AEGC programs that reduce program development time. OSHA estimates that an EEET will take one hour to develop a written AEGC program. The total burden hours and cost of the development of this program is:

		Burden hours:  73.63 establishments x 1 hour = 73.63 hours 
		                Cost:  73.63 hours x $47.80 = $3,519.51

This provision also requires employers to maintain the written AEGC programs at the jobsite, and to disclose the programs to OSHA compliance officers and affected employees.  The Agency estimates that an EEET requires one minute (.02 hour) each year maintaining written program. 
Based on these estimates, the total time for an EEET to maintain the program is one minute (.02 hour).  Therefore, the Agency estimates that the total annual burden hours and cost for these information collection requirements are:

        Burden hours:  73.63 establishments x .02 hour to maintain = 1.47 hour 
		                Cost:  1.47 hour x $47.80 = $70.27

Paragraph (b)(3)(ii)(C)(6)--Tests performed as required in paragraph (b)(3)(ii)(C) of this section shall be recorded. This test record shall identify each receptacle, cord set, and cord- and plug-connected equipment that passed the test and shall indicate the last date it was tested or the interval for which it was tested.  This record shall be kept by means of logs, color coding, or other effective means and shall be maintained until replaced by a more current record.  The record shall be made available on the jobsite for inspection by the Assistant Secretary and any affected employee.

OSHA believes that the 73.63 establishments with written AEGC programs test equipment and record the test results four times a year.  It also estimates that an EEET takes three minutes (.05 hour) to perform each test and two minutes (.03 hour) to record the test results, for a total test-and record time of five minutes (5/60 hour).  These requirements result in total annual burden hour and cost estimates of:

	Burden hours:  73.63 establishments x 4 tests/year x 5/60 hour = 24.54 hours
                Cost:  24.54 hours x $47.80 = $1,173.01

Total burden hours for AEGC programs: 73.63 hours + 1.47 hours + 24.54 hours = 93 hours
Total cost:  $3,519.51 + $70.27 + $1,173.01 = $4,762.79 
   
 §1910.306(c) -- Specific purpose equipment and installations. 

Paragraph (6)(i)--Where there is more than one driving machine in a machine room, the disconnecting means shall be numbered to correspond to the identifying number of the driving machine that they control.

In meeting this requirement, OSHA estimates that identifying and correctly numbering the disconnecting means takes an EEET eight minutes (.13 hour), and that 20% (490.86) of the new establishments must perform this task (2,454.29 new establishments x .20 = 490.86 new establishments).  Accordingly, the estimated total annual burden hours and cost for this requirement are:

	Burden hours:  490.86 new establishments x .13 hour = 63.81 hours
                   Cost:  63.81 hours x $47.80 = $3,050.12

Paragraph (6)(ii)--The disconnecting means shall be provided with a sign to identify the location of the supply-side overcurrent protective device.

OSHA assumes that all new establishments must post one sign to identify the location of the supply-side overcurrent protective device, and that an EEET performs this task in eight minutes (8/60 hour).  This requirement results in the following total annual burden hour and cost estimates:

           Burden hours:	2,454.29 new establishments x .13 hour = 319.06 hours
                  Cost:	319.06 hours x $47.80 = $15,251.07 

      ▪	§1910.306(k) --- Carnivals, circuses, fairs, and similar events

Paragraph (4)(iv)(B)--Single-pole separable connectors used in portable professional motion picture and television equipment may be interchangeable for ac or dc use or for different current ratings on the same premises only if they are listed for ac/dc use and marked to identify the system to which they are connected;

The Agency estimates that .5% (12.27) of the new establishments use interchangeable single-pole separable connectors in portable professional motion pictures and television equipment (2,454.29 new establishments x .005 = 12.27 new establishments), and that an EEET requires eight minutes (.13 hour) to list the connectors for ac/dc use and mark them to identify the system to which they are connected.  Therefore, OSHA estimates the total annual burden hours and cost of this requirement are:

           Burden hours:	12.27 new establishments x .13 hour = 1.60 hours
                  Cost:	1.60 hours x $47.80 = $76.48

 §1910.307(b) -- Documentation 

Paragraph (b)--All areas designated as hazardous (classified) locations under the Class and Zone system and areas designated under the Class and Division system established after August 13, 2007 shall be properly documented.  This documentation shall be available to those authorized to design, install, inspect, maintain, or operate electric equipment at the location.

This documentation consists of area-classification drawings that provide information for designers, installers, inspectors, and other personnel who must ensure that electrical equipment installed and maintained at hazardous (classified) locations meets the certification requirements specified elsewhere in the Standard.  The Agency assumes that 40% (981.72) of the new establishments will require this documentation (2,454.29 new establishments x .4 = 981.72 new establishments) for one of these locations, and that an electrical certified engineer takes four hours to produce this documentation.  Consequently, the estimated total annual burden hours and cost for this documentation are:

	Burden hours:	981.72 new establishments x 4 hours = 3,926.88 hours
                  Cost:	3,926.88 hours x $74.18 = $291,295.96

 §1910.308(b) -- Emergency power system 

Paragraph (b)(3)(i)--A sign shall be placed at the service entrance equipment indicating the type and location of on-site emergency power sources.  However, a sign is not required for individual unit equipment.

According to OSHA's estimates, an engineering manager takes one minute 1/60 hour) to brief an EEET about the required task, and five minutes (5/60 hour) for the EEET to place the sign.  The Agency assumes that 30% (736.29) of the new establishments must acquire and place one of these signs (2,454.29 new establishments x .3 = 736.29 new establishments).  The resulting annual total burden hour and cost estimates are:
      
           Burden hours:	736.29 new establishments x .02 hour = 14.73 hours
			736.29 new establishments x 5/60 hour = 61.36 hours
 Total burden hours:  76.09 hours

		          Cost:	14.73 hours x $110.64 = $1,629.73
			61.36 hours x $47.80 = $2,933.01 
		 Total cost:  $4,562.74 

Paragraph (b)(3)(ii)--Where the grounded circuit conductor connected to the emergency source is connected to a grounding electrode conductor at a location remote from the emergency source, there shall be a sign at the grounding location that shall identify all emergency and normal sources connected at that location.

To meet this requirement, the Agency estimates that an engineering manager takes one minute (.02 hour) to brief an EEET regarding the required task, and five minutes (5/60 hour) for the EEET to place the sign.  OSHA believes that 2% (49.09) of the new establishments must acquire and place one of these signs (2,454.29 new establishments x .02 = 49.09 new establishments).  The Agency estimates the annual total burden hours and cost of this 1requirement to be:

	Burden hours:	49.09 new establishments x .02 hour = 0.98 hours
			49.09 new establishments x 5/60 hour = 4.09 hours
 Total burden hours:  5.07 hours

		          Cost:	0.98 hour x $110.64 = $108.43
			4.09 hours x $47.80 = $195.5
                  Total cost:  $303.93

 1910.333--Selection and use of work practices.

Procedures.  Paragraph 1910.333(b)(2)(i) requires employers to maintain a written copy of the lockout and tagging procedure outlined in paragraph (b)(2) of this standard, and to make it available for inspection by employees and by the Assistant Secretary of Labor and his/her authorized representatives.  The written procedures may be a copy of paragraph (b) of this standard.

OSHA estimates that it will take 15 minutes (.25 hours) to record and maintain a written copy of the procedure outlined in requirement.  Only 85% of the establishment will need a written copy of the procedure to use for tagging 2,454.29 establishments x .85 =2,086.15).

		Burden hours:   2,086.15 new establishments x 1 procedure x .25 hour = 521.54
							hours
			    Cost:    521.54 hours x $47.80 = $24,929.61

Application of locks and tags.  Paragraph 1910.333(b)(2)(iii)(B) requires employers to ensure that each tag used contains a statement prohibiting unauthorized operation of the disconnecting means and removal of the tag.

These tags alert unqualified and unauthorized employees of the presence of electrical hazards, and notify other employee in the vicinity of the need to exercise caution when they are near electrical hazards. 

The Agency assumes that each establishment will use one tag for each system and that an electrician spends three minutes 3/60 hour) tagging each disconnect.  OSHA estimates that only 85% of the establishment (2,086.15) will need to use lockout and tagging (2,454.29 establishments x 0.85 = 2,086.15)

		Burden hours:   2,086.15 new establishments x 1 tags x .05 hour = 104.31 hours
			    Cost:   104.31 hours x $47.80 = $4,986.02

Paragraph 1910.333(b)(2)(v)(B) requires employers to warn employees exposed to the hazards associated with reenergizing the circuit or equipment to stay clear of the circuits and equipment.

These warning signs and marks alert unqualified and unauthorized employees of the presence of electrical hazards, and notify electricians of the need to exercise caution and to take other measures to protect themselves when they are near electrical hazards. 

OSHA estimates that it will take five minutes (5/60 hour) to acquire and post the warning sign.  (2,454.29 establishments x 9 = 22,088.61 jobsites) Only 15% of the jobsites (22,088.61 jobsites x .15 = 3,313.29) will need to use new signs.

	    	Burden hours:   3,313.29 x 1 sign x 5/60 hour = 276.11 hours
			    Cost:   276.11 hours x $47.80 = $13,198.06

     TABLE 2--Electrical Standards for Construction and General Industry:
           Estimated Summary of Burden Hours and Cost per Response.

                                       
                                       
                                       
                            Information Collection
                                 Requirements
                             Number of Respondents
                            Frequency per response
                                Total Responses
                               Time per response
                                   Requested
                                 Burden Hours
                                   Wage Rate
Cost Under Item 12
                                       
                                       
                                       a
                                       b
                                   c = a x b
                                       d
                                   e = c x d
                                       f
                                   g = e x f
                        Construction Standards  -  1926
1
§§1926.403(h); 1910.303(f)--Identification of disconnecting means and circuits.

                                   6,099,462
                                     0.01
                                   60,994.62
                                     5/60
                                     hours
                                   5,082.89
                                       
                                    $47.80
                                       
                                  $242,962.14
2
§§1926.403(i)(2)(iii); 1910.303 (g)(2)(iii)--600 Volts, nominal, or less.--Guarding of live parts.

                                   6,099,462
                                     0.05
                                  304,973.1*
                                     3/60
                                     hours
                                   15,248.67
                                       
                                    $47.80
                                       
                                  $728,885.95
3
§§1926.403(j)(2)(ii); 1910.303 (h)(2)(iii)(B)--Over 600 Volts, nominal.--Installations accessible to unqualified persons.
                                   6,099,462
                                     0.10
                                  609,946.2*
                                     3/60
                                     Hours
                                   30,497.31
                                       
                                    $47.80
                                       
                                 $1,457,771.42
4
§1926.404(b)(1)(iii)--Assured equipment grounding conductor (AEGC) program.

                                   6,099,462
                                     0.01
                                   60,994.62
                                    1 hour
                                   60,994.62
                                       
                                    $47.80
                                       
                                 $2,915,542.84
                                       
5
§§1926.404 (d)(2)(ii); 1910.304(e)(2)(ii)--Services over 600 volts, nominal--Warning signs.

                                   6,099,462
                                     0.03
                                  182,983.86*
                                     3/60
                                     hours
                                   9,149.19
                                       
                                    $47.80
                                       
                                  $437,331.28
6
§§1926.405(h); 1910.305(h)(8)--Portable cables over 600 volts, nominal.

                                   6,099,462
                                     0.05
                                  304,973.1*
                                     3/60
                                     hours
                                   15,248.66
                                       
                                    $47.80
                                       
                                 $728,885.95*
7
§§1926.405(j)(4)(ii)(A); 1910.305(j)(4) (ii)--Disconnecting means for motor-branch circuits.

                                   6,099,462
                                     0.02
                                 121,989.24**
                                     5/60
                                     hours
                                   10,165.77
                                       
                                    $47.80
                                       
                                 $485923.81**
8
§§1926.405(j)(5)(ii); 1910.305(j)(5)(ii)- Transformer operating voltages.

                                   6,099,462
                                     0.05
                                  304,973.1*
                                     3/60
                                     hours
                                   15,248.66
                                       
                                    $47.80
                                       
                                 $728,885.95*
9
§§1926.405(j)(6)(ii)(A); 1910.305(j)(6)(ii)(C)--Equipment for general use--Capacitors.

                                   6,099,462
                                     0.02
                                  121,989.24*
                                     3/60
                                     Hours
                                       
                                    6099.46
                                       
                                    $47.80
                                       
                                 $291,554.19*
10
§§1926.408(a)(2)(iii); 1910.308(a)(2)(iii)--Equipment isolating means.

                                   6,099,462
                                     0.01
                                  60,994.62*
                                     3/60
                                     hours
                                   3,049.73
                                       
                                    $47.80
                                       
                                 $145,777.09*
11
§§1926.408(a)(3)(i); 1910.308(a)(3)(i)-- Power cable connections to mobile machines.

                                   6,099,462
                                     0.02
                                  121,989.24*
                                     3/60
                                     hours
                                    6099.46
                                    $47.80
                                       
                                 $291,554.19*
12
§§1926.408(a)(3)(ii); 1910.308(a)(3)(ii)--Mobile and portable equipment.

                                   6,099,462
                                     0.02
                                  121,989.24*
                                     3/60
                                     hours
                                    6099.46
                                       
                                    $47.80
                                       
                                 $291,554.19*
13
§§1926.416(a)(3)--General requirements--Protection of
employees. 
                                   6,099,462
                                     0.02
                                  121,989.24*
                                     3/60
                                     hours
                                    6099.46
                                       
                                    $47.80
                                       
                                 $291,554.19*
14
§1926.417(a), (b), and (c)--Lockout and tagging of circuits.
 
                                   6,099,462
                                     0.05
                                   304,973.1
                                     1/60
                                     hours
                                    6099.46
                                       
                                    $47.80
                                       
                                  $291,554.19
                         General Industry  -  1910   
15
§1910.303(f)(5)(i)&(ii)--Disconnecting means and circuits.

                                   2,454.29
                                     0.75
                                   1,840.72
                                     2/60
                                     hours
                                     55.22
                                       
                                    $47.80
                                       
                                   $2,639.52
16
§1910.304(b)(1)--Branch circuits-- Identification of multiwire branch circuits.

                                   2,454.29
                                     0.75
                                  1,840.72**
                                     1/60
                                     hours
                                     36.81
                                       
                                    $47.80
                                       
                                  $1,759.52**
                                       
17
§1910.304 (b)(3)(ii)(C)(1) &(6)-- Ground-fault circuit interrupter protection for personnel.

                                   2,454.29
                                     0.18
                                      420
                                     66/60
                                     hour
                                      93
                                       
                                    $47.80
                                       
                                   $4,762.79
18
§1910.306(c)(6)(i)--Specific purpose equipment and installations-- Identification and signs.

                                   2,454.29
                                     0.20
                                    490.86*
                                     8/60
                                     hours
                                     63.81
                                    $47.80
                                       
                                  $3,050.12*
19
§1910.306(c)(6)(ii)--Specific purpose equipment and installations-- Identification and signs.

                                   2,454.29
                                       1
                                   2,454.29*
                                     8/60
                                     hours
                                    319.06
                                       
                                    $47.80
                                       
                                  $15,251.07*
20
§1910.306(k)(4)(iv)(B)--Carnivals, circuses, fairs, and similar events--Portable distribution and termination boxes. 

                                   2,454.29
                                     0.005
                                     12.27
                                     8/60
                                     hours
                                       2
                                       
                                    $47.80
                                       
                                    $76.48
21
§1910.307(b)--Documentation.

                                   2,454.29
                                    0.3999
                                    981.72
                                    4 hours
                                   3,926.88
                                    $74.18
                                  $291,295.96
22
§1910.308 (b)(3)(i)--Emergency power system.

                                   2,454.29
                                    0.60009
                                     1,400
                                     6/60
                                     hours
                                     76.09
                                       
                                    $142.87
                                       
                                   $4,562.74
23
§1910.308(b)(3)(ii)--Emergency power system.

                                   2,454.29
                                    0.04029
                                      94
                                     6/60
                                     hours
                                       5
                                       
                                    $142.87
                                       
                                    $303.93
24
1910.333(b)(2)(i)--Selection and use of work practices--Procedures.
                                   2,454.29
                                    0.84998
                                   2,086.15
                                     15/60
                                     hours
                                    521.54
                                       
                                    $47.80
                                       
                                  $24,929.61
25
1910.333(b)(2)(iii)(B)--Selection and use of work practices--Application of locks and tags.

                                   2,454.29
                                    0.84998
                                   2,086.15
                                     3/60
                                     hours
                                       
                                    104.31
                                       
                                    $47.80
                                       
                                   $4,986.02
26
1910.333(b)(2)(v)(B)--Selection and use of work practices--Application of locks and tags.

                                   2,454.29
                                    1.35019
                                   3,313.29*
                                     5/60
                                     hours
                                    276.11
                                       
                                    $47.80
                                       
                                  $13,198.06*
27
TOTAL
                                       
                                       
                                   2,822,871
                                       
                                    200,662
                                       
                                       
                                  $9,592,961
                                       

	*All employers who need to purchase signs.
	**All employers who need to purchase labels.

13.  Provide an estimate of the total annual cost burden to respondents or recordkeepers resulting from the collection of information.  (Do not include the cost of any hour burden shown in Items 12 and 14.)
 
 The cost estimate should be split into two components:  (a) a total capital and start-up cost component annualized over its expected useful life); and (b) a total operation and maintenance and purchase of service component.  The estimates should take into account costs associated with generating, maintaining, and disclosing or providing the information.  Include descriptions of methods used to estimate major cost factors including system and technology acquisition, expected useful life of capital equipment, the discount rate(s), and the time period over which costs will be incurred.  Capital and start-up costs include, among other items, preparations for collecting information such as purchasing computers and software; monitoring, sampling, drilling and testing equipment; and record storage facilities.

 If cost estimates are expected to vary widely, agencies should present ranges of cost burdens and explain the reasons for the variance.  The cost of purchasing or contracting out information collection services should be a part of this cost burden estimate.  In developing cost burden estimates, agencies may consult with a sample of respondent (fewer than 10), utilize the 60-day pre-OMB submission public comment process and use existing economic or regulatory impact analysis associated with the rulemaking containing the information collection, as appropriate.

 Generally, estimates should not include purchases of equipment or services, or portions thereof, made:  (1) prior to October 1, 1995, (2) to achieve regulatory compliance with requirements not associated with the information collection, (3) for reasons other than to provide information or keep records for the government, or (4) as part of customary and usual business or private practices.

Capital Cost Determinations

As noted in Item 12 above, OSHA estimated that §1910.304(b)(1) requires 75% (1,840.72) of the new establishments to label the phase and system of one ungrounded conductor a year and §1926.405(j)(4)(ii) requires warning labels (121,989.24) for the disconnecting means of motor branch circuits.  Therefore, these establishments must purchase a total of 123,829.96 labels to complete the task.  The Agency assumes that each label costs $10.66.  Accordingly, the total cost each year to these employers is:

			Cost: 123,829.96 labels x $10.66 = $1,320,017.14

As noted in Item 12 above, OSHA estimated that new establishments will need to acquire caution or warning signs to guard workers from coming in contact with energized parts.  Therefore, these new establishments must purchase a total of 2,263,354 signs to complete this task.  The Agency assumes that each sign costs $19.19.  Accordingly, the total cost in the first year to these employers is:

			Cost:  2,263,354 signs x $19.19 = $43,433,763.3

Total cost annualized over a five-year period to the employer is: ($1,320,017.14 + $43,433,763.3) / 5 years = $44,753,780.4 / 5 = $8,950,756.08.

This increase in cost is due to the purchase of warning and caution signs. The price of the labels and signs have gone up.

14.  Provide estimates of the annualized cost to the Federal Government.  Also, provide a description of the method used to estimate cost, which should include quantification of hours, operational expenses (such as equipment, overhead, printing, and support staff), any other expense that would not have been incurred without this collection of information.  Agencies also may aggregate cost estimates from Items 12, 13, and 14 into a single table.

There are no costs to the Federal Government.

15.  Explain the reasons for any program changes or adjustments reported.

OSHA is requesting a increase adjustment to the burden hours from 194,976 to 200,662 hours, a total increase of 5,686 burden hours for the Electrical Standards for Construction and General Industry.  This reflects an update of the industry profile information where the estimated number of affected establishments increased.  The price of the purchase of caution and warning signs have increased from $25,476,949 to $44,753,780.4, a difference of $19,276,831.4. The total cost annualized over a five-year period to the employer is $8,950,756.08.
						
16.  For collections of information whose results will be published, outline plans for tabulation, and publication.  Address any complex analytical techniques that will be used.  Provide the time schedule for the entire project, including beginning and ending dates of the collection information, completion of report, publication dates, and other actions.

OSHA will not publish the information collected under the Standards.

17.  If seeking approval to not display the expiration date for OMB approval of the information collection, explain the reasons that display would be appropriate.

OSHA lists current valid control numbers in §§1910.8, 1915.8, 1917.4, 1918.4, and 1926.5 and publishes the expiration date in the Federal Register notice announcing OMB approval of the information collection requirement.  (see 5 CFR 1320.3(f)(3)).   OSHA believes that this is the most appropriate and accurate mechanism to inform interested parties of these expiration dates.

18.  Explain each exception to the certification statement.

OSHA is not seeking an exception to the certification statement.

B. COLLECTION OF INFORMATION EMPLOYING STATISTICAL METHODS

The supporting statement does not contain any collection of information requirements that employ statistical methods.

SEC. 2. Congressional Findings and Purpose
(a) The Congress finds that personal injuries and illnesses arising out of work
situations impose a substantial burden upon, and are a hindrance to, interstate
commerce in terms of lost production, wage loss, medical expenses, and disability
compensation payments.
(b) The Congress declares it to be its purpose and policy, through the exercise of
its powers to regulate commerce among the several States and with foreign
nations and to provide for the general welfare, to assure so far as possible every
working man and woman in the Nation safe and healthful working conditions and
to preserve our human resources --
29 USC 651
(1) by encouraging employers and employees in their efforts to reduce the
number of occupational safety and health hazards at their places of employment,
and to stimulate employers and employees to institute new and to perfect
existing programs for providing safe and healthful working conditions; (2) by
providing that employers and employees have separate but dependent
responsibilities and rights with respect to achieving safe and healthful working
conditions;
(3) by authorizing the Secretary of Labor to set mandatory occupational safety
and health standards applicable to businesses affecting interstate commerce,
and by creating an Occupational Safety and Health Review Commission for
carrying out adjudicatory functions under the Act;
(4) by building upon advances already made through employer and employee
initiative for providing safe and healthful working conditions;
(5) by providing for research in the field of occupational safety and health,
including the psychological factors involved, and by developing innovative
methods, techniques, and approaches for dealing with occupational safety and
health problems;
(6) by exploring ways to discover latent diseases, establishing causal
connections between diseases and work in environmental conditions, and
conducting other research relating to health problems, in recognition of the fact
that occupational health standards present problems often different from those
involved in occupational safety;
(7) by providing medical criteria which will assure insofar as practicable that no
employee will suffer diminished health, functional capacity, or life expectancy as
a result of his work experience;
(8) by providing for training programs to increase the number and competence
of personnel engaged in the field of occupational safety and health; affecting the
OSH Act since its passage in 1970 through January 1, 2004.
(9) by providing for the development and promulgation of occupational safety
and health standards;
(10) by providing an effective enforcement program which shall include a
prohibition against giving advance notice of any inspection and sanctions for any
individual violating this prohibition;
2
(11) by encouraging the States to assume the fullest responsibility for the
administration and enforcement of their occupational safety and health laws by
providing grants to the States to assist in identifying their needs and
responsibilities in the area of occupational safety and health, to develop plans in
accordance with the provisions of this Act, to improve the administration and
enforcement of State occupational safety and health laws, and to conduct
experimental and demonstration projects in connection therewith;
(12) by providing for appropriate reporting procedures with respect to
occupational safety and health which procedures will help achieve the objectives
of this Act and accurately describe the nature of the occupational safety and
health problem;
(13) by encouraging joint labor-management efforts to reduce injuries and
disease arising out of employment.

                  6. Occupational Safety and Health Standards 
29 USC 655: 
(a) Without regard to chapter 5 of title 5, United States Code, or to the other subsections of this section, the Secretary shall, as soon as practicable during the period beginning with the effective date of this Act and ending two years after such date, by rule promulgate as an occupational safety or health standard any national consensus standard, and any established Federal standard, unless he determines that the promulgation of such a standard would not result in improved safety or health for specifically designated employees. In the event of conflict among any such standards, the Secretary shall promulgate the standard which assures the greatest protection of the safety or health of the affected employees. (b) The Secretary may by rule promulgate, modify, or revoke any occupational safety or health standard in the following manner: 
(1) Whenever the Secretary, upon the basis of information submitted to him in writing by an interested person, a representative of any organization of employers or employees, a nationally recognized standards-producing organization, the Secretary of Health and Human Services, the National Institute for Occupational Safety and Health, or a State or political subdivision, or on the basis of information developed by the Secretary or otherwise available to him, determines that a rule should be promulgated in order to serve the objectives of this Act, the Secretary may request the recommendations of an advisory committee appointed under section 7 of this Act. The Secretary shall provide such an advisory committee with any proposals of his own or of the Secretary of Health and Human Services, together with all pertinent factual information developed by the Secretary or the Secretary of Health and Human Services, or otherwise available, including the results of research, demonstrations, and experiments. An advisory committee shall submit to the Secretary its recommendations regarding the rule to be promulgated within ninety days from the date of its appointment or within such longer or shorter period as may be prescribed by the Secretary, but in no event for a period which is longer than two hundred and seventy days. (2) The Secretary shall publish a proposed rule promulgating, modifying, or revoking an occupational safety or health standard in the Federal Register and shall afford interested persons a period of thirty days after publication to submit written data or comments. Where an advisory committee is appointed and the Secretary determines that a rule should be issued, he shall publish the proposed rule within sixty days after the submission of the advisory committee's recommendations or the expiration of the period prescribed by the Secretary for such submission. (3) On or before the last day of the period provided for the submission of written data or comments under paragraph (2), any interested person may file with the Secretary written objections to the proposed rule, stating the grounds therefore and requesting a public hearing on such objections. Within thirty days after the last day for filing such objections, the Secretary shall publish in the Federal Register a notice specifying the occupational safety or health standard to which objections have been filed and a hearing requested, and specifying a time and place for such hearing. 

            SEC. 8. Inspections, Investigations, and Recordkeeping 
(a) In order to carry out the purposes of this Act, the Secretary, upon presenting appropriate credentials to the owner, operator, or agent in charge, is authorized -- 
29 USC 657 
(1) to enter without delay and at reasonable times any factory, plant, establishment, construction site, or other area, workplace or environment where work is performed by an employee of an employer; and (2) to inspect and investigate during regular working hours and at other reasonable times, and within reasonable limits and in a reasonable manner, any such place of employment and all pertinent conditions, structures, machines, apparatus, devices, equipment, and materials therein, and to question privately any such employer, owner, operator, agent or employee. 
(b) In making his inspections and investigations under this Act the Secretary may require the attendance and testimony of witnesses and the production of evidence under oath. Witnesses shall be paid the same fees and mileage that are paid witnesses in the courts of the United States. In case of a contumacy, failure, or refusal of any person to obey such an order, any district court of the United States or the United States courts of any territory or possession, within the jurisdiction of which such person is found, or resides or transacts business, upon the application by the Secretary, shall have jurisdiction to issue to such person an order requiring such person to appear to produce evidence if, as, and when so ordered, and to give testimony relating to the matter under investigation or in question, and any failure to obey such order of the court may be punished by said court as a contempt thereof. (c) (1) Each employer shall make, keep and preserve, and make available to the Secretary or the Secretary of Health and Human Services, such records regarding his activities relating to this Act as the Secretary, in cooperation with the Secretary of Health and Human Services, may prescribe by regulation as necessary or appropriate for the enforcement of this Act or for developing information regarding the causes and prevention of occupational accidents and illnesses. In order to carry out the provisions of this paragraph such regulations may include provisions requiring employers to conduct periodic inspections. The Secretary shall also issue regulations requiring that employers, through posting of notices or other appropriate means, keep their employees informed of their protections and obligations under this Act, including the provisions of applicable standards. 
(2) The Secretary, in cooperation with the Secretary of Health and Human Services, shall prescribe regulations requiring employers to maintain accurate records of, and to make periodic reports on, work-related deaths, injuries and illnesses other than minor injuries requiring only first aid treatment and which do not involve medical treatment, loss of consciousness, restriction of work or motion, or transfer to another job. 
Electronic Code of Federal Regulations
e-CFR data is current as of May 24, 2021
Title 29: Labor 
PART 1926 -- SAFETY AND HEALTH REGULATIONS FOR CONSTRUCTION 

Subpart K -- Electrical

General
§1926.400   Introduction.
    This subpart addresses electrical safety requirements that are necessary for the practical safeguarding of employees involved in construction work and is divided into four major divisions and applicable definitions as follows:
    (a) Installation safety requirements. Installation safety requirements are contained in §§1926.402 through 1926.408. Included in this category are electric equipment and installations used to provide electric power and light on jobsites.
    (b) Safety-related work practices. Safety-related work practices are contained in §§1926.416 and 1926.417. In addition to covering the hazards arising from the use of electricity at jobsites, these regulations also cover the hazards arising from the accidental contact, direct or indirect, by employees with all energized lines, above or below ground, passing through or near the jobsite.
    (c) Safety-related maintenance and environmental considerations. Safety-related maintenance and environmental considerations are contained in §§1926.431 and 1926.432.
    (d) Safety requirements for special equipment. Safety requirements for special equipment are contained in §1926.441.
    (e) Definitions. Definitions applicable to this subpart are contained in §1926.449.
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§1926.401   [Reserved]
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Installation Safety Requirements
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§1926.402   Applicability.
    (a) Covered. Sections 1926.402 through 1926.408 contain installation safety requirements for electrical equipment and installations used to provide electric power and light at the jobsite. These sections apply to installations, both temporary and permanent, used on the jobsite; but these sections do not apply to existing permanent installations that were in place before the construction activity commenced.
    Note: If the electrical installation is made in accordance with the National Electrical Code ANSI/NFPA 70-1984, exclusive of Formal Interpretations and Tentative Interim Amendments, it will be deemed to be in compliance with §§1926.403 through 1926.408, except for §§1926.404(b)(1) and 1926.405(a)(2)(ii) (E), (F), (G), and (J).
    (b) Not covered. Sections 1926.402 through 1926.408 do not cover installations used for the generation, transmission, and distribution of electric energy, including related communication, metering, control, and transformation installations. (However, these regulations do cover portable and vehicle-mounted generators used to provide power for equipment used at the jobsite.) See subpart V of this part for the construction of power distribution and transmission lines.
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§1926.403   General requirements.
    (a) Approval. All electrical conductors and equipment shall be approved.
    (b) Examination, installation, and use of equipment -- (1) Examination. The employer shall ensure that electrical equipment is free from recognized hazards that are likely to cause death or serious physical harm to employees. Safety of equipment shall be determined on the basis of the following considerations:
    (i) Suitability for installation and use in conformity with the provisions of this subpart. Suitability of equipment for an identified purpose may be evidenced by listing, labeling, or certification for that identified purpose.
    (ii) Mechanical strength and durability, including, for parts designed to enclose and protect other equipment, the adequacy of the protection thus provided.
    (iii) Electrical insulation.
    (iv) Heating effects under conditions of use.
    (v) Arcing effects.
    (vi) Classification by type, size, voltage, current capacity, specific use.
    (vii) Other factors which contribute to the practical safeguarding of employees using or likely to come in contact with the equipment.
    (2) Installation and use. Listed, labeled, or certified equipment shall be installed and used in accordance with instructions included in the listing, labeling, or certification.
    (c) Interrupting rating. Equipment intended to break current shall have an interrupting rating at system voltage sufficient for the current that must be interrupted.
    (d) Mounting and cooling of equipment -- (1) Mounting. Electric equipment shall be firmly secured to the surface on which it is mounted. Wooden plugs driven into holes in masonry, concrete, plaster, or similar materials shall not be used.
    (2) Cooling. Electrical equipment which depends upon the natural circulation of air and convection principles for cooling of exposed surfaces shall be installed so that room air flow over such surfaces is not prevented by walls or by adjacent installed equipment. For equipment designed for floor mounting, clearance between top surfaces and adjacent surfaces shall be provided to dissipate rising warm air. Electrical equipment provided with ventilating openings shall be installed so that walls or other obstructions do not prevent the free circulation of air through the equipment.
    (e) Splices. Conductors shall be spliced or joined with splicing devices designed for the use or by brazing, welding, or soldering with a fusible metal or alloy. Soldered splices shall first be so spliced or joined as to be mechanically and electrically secure without solder and then soldered. All splices and joints and the free ends of conductors shall be covered with an insulation equivalent to that of the conductors or with an insulating device designed for the purpose.
    (f) Arcing parts. Parts of electric equipment which in ordinary operation produce arcs, sparks, flames, or molten metal shall be enclosed or separated and isolated from all combustible material.
    (g) Marking. Electrical equipment shall not be used unless the manufacturer's name, trademark, or other descriptive marking by which the organization responsible for the product may be identified is placed on the equipment and unless other markings are provided giving voltage, current, wattage, or other ratings as necessary. The marking shall be of sufficient durability to withstand the environment involved.
    (h) Identification of disconnecting means and circuits. Each disconnecting means required by this subpart for motors and appliances shall be legibly marked to indicate its purpose, unless located and arranged so the purpose is evident. Each service, feeder, and branch circuit, at its disconnecting means or overcurrent device, shall be legibly marked to indicate its purpose, unless located and arranged so the purpose is evident. These markings shall be of sufficient durability to withstand the environment involved.
    (i) 600 Volts, nominal, or less. This paragraph applies to equipment operating at 600 volts, nominal, or less.
    (1) Working space about electric equipment. Sufficient access and working space shall be provided and maintained about all electric equipment to permit ready and safe operation and maintenance of such equipment.
    (i) Working clearances. Except as required or permitted elsewhere in this subpart, the dimension of the working space in the direction of access to live parts operating at 600 volts or less and likely to require examination, adjustment, servicing, or maintenance while alive shall not be less than indicated in Table K-1. In addition to the dimensions shown in Table K-1, workspace shall not be less than 30 inches (762 mm) wide in front of the electric equipment. Distances shall be measured from the live parts if they are exposed, or from the enclosure front or opening if the live parts are enclosed. Walls constructed of concrete, brick, or tile are considered to be grounded. Working space is not required in back of assemblies such as dead-front switchboards or motor control centers where there are no renewable or adjustable parts such as fuses or switches on the back and where all connections are accessible from locations other than the back.
                          Table K-1 -- Working Clearances
                           Nominal voltage to ground
                   Minimum clear distance for conditions[1]
                                       
                                      (a)
                                      (b)
                                      (c)
   
                                                                        Feet[2]
                                                                        Feet[2]
                                                                        Feet[2]
0-150
                                                                              3
                                                                              3
                                                                              3
151-600
                                                                              3
                                                                      3[1]⁄2 
                                                                              4
    1Conditions (a), (b), and (c) are as follows: (a) Exposed live parts on one side and no live or grounded parts on the other side of the working space, or exposed live parts on both sides effectively guarded by insulating material. Insulated wire or insulated busbars operating at not over 300 volts are not considered live parts. (b) Exposed live parts on one side and grounded parts on the other side. (c) Exposed live parts on both sides of the workspace [not guarded as provided in Condition (a)] with the operator between.
    2Note: For International System of Units (SI): one foot = 0.3048m.
    (ii) Clear spaces. Working space required by this subpart shall not be used for storage. When normally enclosed live parts are exposed for inspection or servicing, the working space, if in a passageway or general open space, shall be guarded.
    (iii) Access and entrance to working space. At least one entrance shall be provided to give access to the working space about electric equipment.
    (iv) Front working space. Where there are live parts normally exposed on the front of switchboards or motor control centers, the working space in front of such equipment shall not be less than 3 feet (914 mm).
    (v) Headroom. The minimum headroom of working spaces about service equipment, switchboards, panelboards, or motor control centers shall be 6 feet 3 inches (1.91 m).
    (2) Guarding of live parts. (i) Except as required or permitted elsewhere in this subpart, live parts of electric equipment operating at 50 volts or more shall be guarded against accidental contact by cabinets or other forms of enclosures, or by any of the following means:
    (A) By location in a room, vault, or similar enclosure that is accessible only to qualified persons.
    (B) By partitions or screens so arranged that only qualified persons will have access to the space within reach of the live parts. Any openings in such partitions or screens shall be so sized and located that persons are not likely to come into accidental contact with the live parts or to bring conducting objects into contact with them.
    (C) By location on a balcony, gallery, or platform so elevated and arranged as to exclude unqualified persons.
    (D) By elevation of 8 feet (2.44 m) or more above the floor or other working surface and so installed as to exclude unqualified persons.
    (ii) In locations where electric equipment would be exposed to physical damage, enclosures or guards shall be so arranged and of such strength as to prevent such damage.
    (iii) Entrances to rooms and other guarded locations containing exposed live parts shall be marked with conspicuous warning signs forbidding unqualified persons to enter.
    (j) Over 600 volts, nominal -- (1) General. Conductors and equipment used on circuits exceeding 600 volts, nominal, shall comply with all applicable provisions of paragraphs (a) through (g) of this section and with the following provisions which supplement or modify those requirements. The provisions of paragraphs (j)(2), (j)(3), and (j)(4) of this section do not apply to equipment on the supply side of the service conductors.
    (2) Enclosure for electrical installations. Electrical installations in a vault, room, closet or in an area surrounded by a wall, screen, or fence, access to which is controlled by lock and key or other equivalent means, are considered to be accessible to qualified persons only. A wall, screen, or fence less than 8 feet (2.44 m) in height is not considered adequate to prevent access unless it has other features that provide a degree of isolation equivalent to an 8-foot (2.44-m) fence. The entrances to all buildings, rooms or enclosures containing exposed live parts or exposed conductors operating at over 600 volts, nominal, shall be kept locked or shall be under the observation of a qualified person at all times.
    (i) Installations accessible to qualified persons only. Electrical installations having exposed live parts shall be accessible to qualified persons only and shall comply with the applicable provisions of paragraph (j)(3) of this section.
    (ii) Installations accessible to unqualified persons. Electrical installations that are open to unqualified persons shall be made with metal-enclosed equipment or shall be enclosed in a vault or in an area, access to which is controlled by a lock. Metal-enclosed switchgear, unit substations, transformers, pull boxes, connection boxes, and other similar associated equipment shall be marked with appropriate caution signs. If equipment is exposed to physical damage from vehicular traffic, guards shall be provided to prevent such damage. Ventilating or similar openings in metal-enclosed equipment shall be designed so that foreign objects inserted through these openings will be deflected from energized parts.
    (3) Workspace about equipment. Sufficient space shall be provided and maintained about electric equipment to permit ready and safe operation and maintenance of such equipment. Where energized parts are exposed, the minimum clear workspace shall not be less than 6 feet 6 inches (1.98 m) high (measured vertically from the floor or platform), or less than 3 feet (914 mm) wide (measured parallel to the equipment). The depth shall be as required in Table K-2. The workspace shall be adequate to permit at least a 90-degree opening of doors or hinged panels.
    (i) Working space. The minimum clear working space in front of electric equipment such as switchboards, control panels, switches, circuit breakers, motor controllers, relays, and similar equipment shall not be less than specified in Table K-2 unless otherwise specified in this subpart. Distances shall be measured from the live parts if they are exposed, or from the enclosure front or opening if the live parts are enclosed. However, working space is not required in back of equipment such as deadfront switchboards or control assemblies where there are no renewable or adjustable parts (such as fuses or switches) on the back and where all connections are accessible from locations other than the back. Where rear access is required to work on de-energized parts on the back of enclosed equipment, a minimum working space of 30 inches (762 mm) horizontally shall be provided.
    Table K-2 -- Minimum Depth of Clear Working Space in Front of Electric Equipment
                           Nominal voltage to ground
                                 Conditions[1]
                                       
                                      (a)
                                      (b)
                                      (c)
                                       
                                    Feet[2]
                                    Feet[2]
                                    Feet[2]
601 to 2,500
                                                                              3
                                                                              4
                                                                              5
2,501 to 9,000
                                                                              4
                                                                              5
                                                                              6
9,001 to 25,000
                                                                              5
                                                                              6
                                                                              9
25,001 to 75 kV
                                                                              6
                                                                              8
                                                                             10
Above 75kV
                                                                              8
                                                                             10
                                                                             12
    1Conditions (a), (b), and (c) are as follows: (a) Exposed live parts on one side and no live or grounded parts on the other side of the working space, or exposed live parts on both sides effectively guarded by insulating materials. Insulated wire or insulated busbars operating at not over 300 volts are not considered live parts. (b) Exposed live parts on one side and grounded parts on the other side. Walls constructed of concrete, brick, or tile are considered to be grounded surfaces. (c) Exposed live parts on both sides of the workspace [not guarded as provided in Condition (a)] with the operator between.
    2Note: For SI units: one foot = 0.3048 m.
    (ii) Lighting outlets and points of control. The lighting outlets shall be so arranged that persons changing lamps or making repairs on the lighting system will not be endangered by live parts or other equipment. The points of control shall be so located that persons are not likely to come in contact with any live part or moving part of the equipment while turning on the lights.
    (iii) Elevation of unguarded live parts. Unguarded live parts above working space shall be maintained at elevations not less than specified in Table K-3.
      Table K-3 -- Elevation of Unguarded Energized Parts Above Working Space
                        Nominal voltage between phases
                               Minimum elevation
601-7,500
8 feet 6 inches.[1]
7,501-35,000
9 feet.
Over 35kV
9 feet + 0.37 inches per kV above 35kV.
    1Note: For SI units: one inch = 25.4 mm; one foot = 0.3048 m.
    (4) Entrance and access to workspace. At least one entrance not less than 24 inches (610 mm) wide and 6 feet 6 inches (1.98 m) high shall be provided to give access to the working space about electric equipment. On switchboard and control panels exceeding 48 inches (1.22 m) in width, there shall be one entrance at each end of such board where practicable. Where bare energized parts at any voltage or insulated energized parts above 600 volts are located adjacent to such entrance, they shall be guarded.
[51 FR 25318, July 11, 1986, as amended at 61 FR 5510, Feb. 13, 1996]
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§1926.404   Wiring design and protection.
    (a) Use and identification of grounded and grounding conductors -- (1) Identification of conductors. A conductor used as a grounded conductor shall be identifiable and distinguishable from all other conductors. A conductor used as an equipment grounding conductor shall be identifiable and distinguishable from all other conductors.
    (2) Polarity of connections. No grounded conductor shall be attached to any terminal or lead so as to reverse designated polarity.
    (3) Use of grounding terminals and devices. A grounding terminal or grounding-type device on a receptacle, cord connector, or attachment plug shall not be used for purposes other than grounding.
    (b) Branch circuits -- (1) Ground-fault protection -- (i) General. The employer shall use either ground fault circuit interrupters as specified in paragraph (b)(1)(ii) of this section or an assured equipment grounding conductor program as specified in paragraph (b)(1)(iii) of this section to protect employees on construction sites. These requirements are in addition to any other requirements for equipment grounding conductors.
    (ii) Ground-fault circuit interrupters. All 120-volt, single-phase, 15- and 20-ampere receptacle outlets on construction sites, which are not a part of the permanent wiring of the building or structure and which are in use by employees, shall have approved ground-fault circuit interrupters for personnel protection. Receptacles on a two-wire, single-phase portable or vehicle-mounted generator rated not more than 5kW, where the circuit conductors of the generator are insulated from the generator frame and all other grounded surfaces, need not be protected with ground-fault circuit interrupters.
    (iii) Assured equipment grounding conductor program. The employer shall establish and implement an assured equipment grounding conductor program on construction sites covering all cord sets, receptacles which are not a part of the building or structure, and equipment connected by cord and plug which are available for use or used by employees. This program shall comply with the following minimum requirements:
    (A) A written description of the program, including the specific procedures adopted by the employer, shall be available at the jobsite for inspection and copying by the Assistant Secretary and any affected employee.
    (B) The employer shall designate one or more competent persons (as defined in §1926.32(f)) to implement the program.
    (C) Each cord set, attachment cap, plug and receptacle of cord sets, and any equipment connected by cord and plug, except cord sets and receptacles which are fixed and not exposed to damage, shall be visually inspected before each day's use for external defects, such as deformed or missing pins or insulation damage, and for indications of possible internal damage. Equipment found damaged or defective shall not be used until repaired.
    (D) The following tests shall be performed on all cord sets, receptacles which are not a part of the permanent wiring of the building or structure, and cord- and plug-connected equipment required to be grounded:
    (1) All equipment grounding conductors shall be tested for continuity and shall be electrically continuous.
    (2) Each receptacle and attachment cap or plug shall be tested for correct attachment of the equipment grounding conductor. The equipment grounding conductor shall be connected to its proper terminal.
    (E) All required tests shall be performed:
    (1) Before first use;
    (2) Before equipment is returned to service following any repairs;
    (3) Before equipment is used after any incident which can be reasonably suspected to have caused damage (for example, when a cord set is run over); and
    (4) At intervals not to exceed 3 months, except that cord sets and receptacles which are fixed and not exposed to damage shall be tested at intervals not exceeding 6 months.
    (F) The employer shall not make available or permit the use by employees of any equipment which has not met the requirements of this paragraph (b)(1)(iii) of this section.
    (G) Tests performed as required in this paragraph shall be recorded. This test record shall identify each receptacle, cord set, and cord- and plug-connected equipment that passed the test and shall indicate the last date it was tested or the interval for which it was tested. This record shall be kept by means of logs, color coding, or other effective means and shall be maintained until replaced by a more current record. The record shall be made available on the jobsite for inspection by the Assistant Secretary and any affected employee.
    (2) Outlet devices. Outlet devices shall have an ampere rating not less than the load to be served and shall comply with the following:
    (i) Single receptacles. A single receptacle installed on an individual branch circuit shall have an ampere rating of not less than that of the branch circuit.
    (ii) Two or more receptacles. Where connected to a branch circuit supplying two or more receptacles or outlets, receptacle ratings shall conform to the values listed in Table K-4.
    (iii) Receptacles used for the connection of motors. The rating of an attachment plug or receptacle used for cord- and plug-connection of a motor to a branch circuit shall not exceed 15 amperes at 125 volts or 10 amperes at 250 volts if individual overload protection is omitted.
             Table K-4 -- Receptacle Ratings for Various Size Circuits
                            Circuit rating amperes
                           Receptacle rating amperes
15
Not over 15.
20
15 or 20.
30
30.
40
40 or 50.
50
50.
    (c) Outside conductors and lamps -- (1) 600 volts, nominal, or less. Paragraphs (c)(1)(i) through (c)(1)(iv) of this section apply to branch circuit, feeder, and service conductors rated 600 volts, nominal, or less and run outdoors as open conductors.
    (i) Conductors on poles. Conductors supported on poles shall provide a horizontal climbing space not less than the following:
    (A) Power conductors below communication conductors -- 30 inches (762 mm) .
    (B) Power conductors alone or above communication conductors: 300 volts or less -- 24 inches (610 mm); more than 300 volts -- 30 inches (762 mm).
    (C) Communication conductors below power conductors: with power conductors 300 volts or less -- 24 inches (610 mm); more than 300 volts -- 30 inches (762 mm).
    (ii) Clearance from ground. Open conductors shall conform to the following minimum clearances:
    (A) 10 feet (3.05 m) -- above finished grade, sidewalks, or from any platform or projection from which they might be reached.
    (B) 12 feet (3.66 m) -- over areas subject to vehicular traffic other than truck traffic.
    (C) 15 feet (4.57 m) -- over areas other than those specified in paragraph (c)(1)(ii)(D) of this section that are subject to truck traffic.
    (D) 18 feet (5.49 m) -- over public streets, alleys, roads, and driveways.
    (iii) Clearance from building openings. Conductors shall have a clearance of at least 3 feet (914 mm) from windows, doors, fire escapes, or similar locations. Conductors run above the top level of a window are considered to be out of reach from that window and, therefore, do not have to be 3 feet (914 mm) away.
    (iv) Clearance over roofs. Conductors above roof space accessible to employees on foot shall have a clearance from the highest point of the roof surface of not less than 8 feet (2.44 m) vertical clearance for insulated conductors, not less than 10 feet (3.05 m) vertical or diagonal clearance for covered conductors, and not less than 15 feet (4.57 m) for bare conductors, except that:
    (A) Where the roof space is also accessible to vehicular traffic, the vertical clearance shall not be less than 18 feet (5.49 m), or
    (B) Where the roof space is not normally accessible to employees on foot, fully insulated conductors shall have a vertical or diagonal clearance of not less than 3 feet (914 mm), or
    (C) Where the voltage between conductors is 300 volts or less and the roof has a slope of not less than 4 inches (102 mm) in 12 inches (305 mm), the clearance from roofs shall be at least 3 feet (914 mm), or
    (D) Where the voltage between conductors is 300 volts or less and the conductors do not pass over more than 4 feet (1.22 m) of the overhang portion of the roof and they are terminated at a through-the-roof raceway or support, the clearance from roofs shall be at least 18 inches (457 mm).
    (2) Location of outdoor lamps. Lamps for outdoor lighting shall be located below all live conductors, transformers, or other electric equipment, unless such equipment is controlled by a disconnecting means that can be locked in the open position or unless adequate clearances or other safeguards are provided for relamping operations.
    (d) Services -- (1) Disconnecting means -- (i) General. Means shall be provided to disconnect all conductors in a building or other structure from the service-entrance conductors. The disconnecting means shall plainly indicate whether it is in the open or closed position and shall be installed at a readily accessible location nearest the point of entrance of the service-entrance conductors.
    (ii) Simultaneous opening of poles. Each service disconnecting means shall simultaneously disconnect all ungrounded conductors.
    (2) Services over 600 volts, nominal. The following additional requirements apply to services over 600 volts, nominal.
    (i) Guarding. Service-entrance conductors installed as open wires shall be guarded to make them accessible only to qualified persons.
    (ii) Warning signs. Signs warning of high voltage shall be posted where unauthorized employees might come in contact with live parts.
    (e) Overcurrent protection -- (1) 600 volts, nominal, or less. The following requirements apply to overcurrent protection of circuits rated 600 volts, nominal, or less.
    (i) Protection of conductors and equipment. Conductors and equipment shall be protected from overcurrent in accordance with their ability to safely conduct current. Conductors shall have sufficient ampacity to carry the load.
    (ii) Grounded conductors. Except for motor-running overload protection, overcurrent devices shall not interrupt the continuity of the grounded conductor unless all conductors of the circuit are opened simultaneously.
    (iii) Disconnection of fuses and thermal cutouts. Except for devices provided for current-limiting on the supply side of the service disconnecting means, all cartridge fuses which are accessible to other than qualified persons and all fuses and thermal cutouts on circuits over 150 volts to ground shall be provided with disconnecting means. This disconnecting means shall be installed so that the fuse or thermal cutout can be disconnected from its supply without disrupting service to equipment and circuits unrelated to those protected by the overcurrent device.
    (iv) Location in or on premises. Overcurrent devices shall be readily accessible. Overcurrent devices shall not be located where they could create an employee safety hazard by being exposed to physical damage or located in the vicinity of easily ignitible material.
    (v) Arcing or suddenly moving parts. Fuses and circuit breakers shall be so located or shielded that employees will not be burned or otherwise injured by their operation.
    (vi) Circuit breakers -- (A) Circuit breakers shall clearly indicate whether they are in the open (off) or closed (on) position.
    (B) Where circuit breaker handles on switchboards are operated vertically rather than horizontally or rotationally, the up position of the handle shall be the closed (on) position.
    (C) If used as switches in 120-volt, fluorescent lighting circuits, circuit breakers shall be marked "SWD."
    (2) Over 600 volts, nominal. Feeders and branch circuits over 600 volts, nominal, shall have short-circuit protection.
    (f) Grounding. Paragraphs (f)(1) through (f)(11) of this section contain grounding requirements for systems, circuits, and equipment.
    (1) Systems to be grounded. The following systems which supply premises wiring shall be grounded:
    (i) Three-wire DC systems. All 3-wire DC systems shall have their neutral conductor grounded.
    (ii) Two-wire DC systems. Two-wire DC systems operating at over 50 volts through 300 volts between conductors shall be grounded unless they are rectifier-derived from an AC system complying with paragraphs (f)(1)(iii), (f)(1)(iv), and (f)(1)(v) of this section.
    (iii) AC circuits, less than 50 volts. AC circuits of less than 50 volts shall be grounded if they are installed as overhead conductors outside of buildings or if they are supplied by transformers and the transformer primary supply system is ungrounded or exceeds 150 volts to ground.
    (iv) AC systems, 50 volts to 1000 volts. AC systems of 50 volts to 1000 volts shall be grounded under any of the following conditions, unless exempted by paragraph (f)(1)(v) of this section:
    (A) If the system can be so grounded that the maximum voltage to ground on the ungrounded conductors does not exceed 150 volts;
    (B) If the system is nominally rated 480Y/277 volt, 3-phase, 4-wire in which the neutral is used as a circuit conductor;
    (C) If the system is nominally rated 240/120 volt, 3-phase, 4-wire in which the midpoint of one phase is used as a circuit conductor; or
    (D) If a service conductor is uninsulated.
    (v) Exceptions. AC systems of 50 volts to 1000 volts are not required to be grounded if the system is separately derived and is supplied by a transformer that has a primary voltage rating less than 1000 volts, provided all of the following conditions are met:
    (A) The system is used exclusively for control circuits,
    (B) The conditions of maintenance and supervision assure that only qualified persons will service the installation,
    (C) Continuity of control power is required, and
    (D) Ground detectors are installed on the control system.
    (2) Separately derived systems. Where paragraph (f)(1) of this section requires grounding of wiring systems whose power is derived from generator, transformer, or converter windings and has no direct electrical connection, including a solidly connected grounded circuit conductor, to supply conductors originating in another system, paragraph (f)(5) of this section shall also apply.
    (3) Portable and vehicle-mounted generators -- (i) Portable generators. Under the following conditions, the frame of a portable generator need not be grounded and may serve as the grounding electrode for a system supplied by the generator:
    (A) The generator supplies only equipment mounted on the generator and/or cord- and plug-connected equipment through receptacles mounted on the generator, and
    (B) The noncurrent-carrying metal parts of equipment and the equipment grounding conductor terminals of the receptacles are bonded to the generator frame.
    (ii) Vehicle-mounted generators. Under the following conditions the frame of a vehicle may serve as the grounding electrode for a system supplied by a generator located on the vehicle:
    (A) The frame of the generator is bonded to the vehicle frame, and
    (B) The generator supplies only equipment located on the vehicle and/or cord- and plug-connected equipment through receptacles mounted on the vehicle or on the generator, and
    (C) The noncurrent-carrying metal parts of equipment and the equipment grounding conductor terminals of the receptacles are bonded to the generator frame, and
    (D) The system complies with all other provisions of this section.
    (iii) Neutral conductor bonding. A neutral conductor shall be bonded to the generator frame if the generator is a component of a separately derived system. No other conductor need be bonded to the generator frame.
    (4) Conductors to be grounded. For AC premises wiring systems the identified conductor shall be grounded.
    (5) Grounding connections -- (i) Grounded system. For a grounded system, a grounding electrode conductor shall be used to connect both the equipment grounding conductor and the grounded circuit conductor to the grounding electrode. Both the equipment grounding conductor and the grounding electrode conductor shall be connected to the grounded circuit conductor on the supply side of the service disconnecting means, or on the supply side of the system disconnecting means or overcurrent devices if the system is separately derived.
    (ii) Ungrounded systems. For an ungrounded service-supplied system, the equipment grounding conductor shall be connected to the grounding electrode conductor at the service equipment. For an ungrounded separately derived system, the equipment grounding conductor shall be connected to the grounding electrode conductor at, or ahead of, the system disconnecting means or overcurrent devices.
    (6) Grounding path. The path to ground from circuits, equipment, and enclosures shall be permanent and continuous.
    (7) Supports, enclosures, and equipment to be grounded -- (i) Supports and enclosures for conductors. Metal cable trays, metal raceways, and metal enclosures for conductors shall be grounded, except that:
    (A) Metal enclosures such as sleeves that are used to protect cable assemblies from physical damage need not be grounded; and
    (B) Metal enclosures for conductors added to existing installations of open wire, knob-and-tube wiring, and nonmetallic-sheathed cable need not be grounded if all of the following conditions are met:
    (1) Runs are less than 25 feet (7.62 m);
    (2) Enclosures are free from probable contact with ground, grounded metal, metal laths, or other conductive materials; and
    (3) Enclosures are guarded against employee contact.
    (ii) Service equipment enclosures. Metal enclosures for service equipment shall be grounded.
    (iii) Fixed equipment. Exposed noncurrent-carrying metal parts of fixed equipment which may become energized shall be grounded under any of the following conditions:
    (A) If within 8 feet (2.44 m) vertically or 5 feet (1.52 m) horizontally of ground or grounded metal objects and subject to employee contact.
    (B) If located in a wet or damp location and subject to employee contact.
    (C) If in electrical contact with metal.
    (D) If in a hazardous (classified) location.
    (E) If supplied by a metal-clad, metal-sheathed, or grounded metal raceway wiring method.
    (F) If equipment operates with any terminal at over 150 volts to ground; however, the following need not be grounded:
    (1) Enclosures for switches or circuit breakers used for other than service equipment and accessible to qualified persons only;
    (2) Metal frames of electrically heated appliances which are permanently and effectively insulated from ground; and
    (3) The cases of distribution apparatus such as transformers and capacitors mounted on wooden poles at a height exceeding 8 feet (2.44 m) above ground or grade level.
    (iv) Equipment connected by cord and plug. Under any of the conditions described in paragraphs (f)(7)(iv)(A) through (f)(7)(iv)(C) of this section, exposed noncurrent-carrying metal parts of cord- and plug-connected equipment which may become energized shall be grounded:
    (A) If in a hazardous (classified) location (see §1926.407).
    (B) If operated at over 150 volts to ground, except for guarded motors and metal frames of electrically heated appliances if the appliance frames are permanently and effectively insulated from ground.
    (C) If the equipment is one of the types listed in paragraphs (f)(7)(iv)(C)(1) through (f)(7)(iv)(C)(5) of this section. However, even though the equipment may be one of these types, it need not be grounded if it is exempted by paragraph (f)(7)(iv)(C)(6).
    (1) Hand held motor-operated tools;
    (2) Cord- and plug-connected equipment used in damp or wet locations or by employees standing on the ground or on metal floors or working inside of metal tanks or boilers;
    (3) Portable and mobile X-ray and associated equipment;
    (4) Tools likely to be used in wet and/or conductive locations; and
    (5) Portable hand lamps.
    (6) Tools likely to be used in wet and/or conductive locations need not be grounded if supplied through an isolating transformer with an ungrounded secondary of not over 50 volts. Listed or labeled portable tools and appliances protected by a system of double insulation, or its equivalent, need not be grounded. If such a system is employed, the equipment shall be distinctively marked to indicate that the tool or appliance utilizes a system of double insulation.
    (v) Nonelectrical equipment. The metal parts of the following nonelectrical equipment shall be grounded: Frames and tracks of electrically operated cranes; frames of nonelectrically driven elevator cars to which electric conductors are attached; hand-operated metal shifting ropes or cables of electric elevators, and metal partitions, grill work, and similar metal enclosures around equipment of over IkV between conductors.
    (8) Methods of grounding equipment -- (i) With circuit conductors. Noncurrent-carrying metal parts of fixed equipment, if required to be grounded by this subpart, shall be grounded by an equipment grounding conductor which is contained within the same raceway, cable, or cord, or runs with or encloses the circuit conductors. For DC circuits only, the equipment grounding conductor may be run separately from the circuit conductors.
    (ii) Grounding conductor. A conductor used for grounding fixed or movable equipment shall have capacity to conduct safely any fault current which may be imposed on it.
    (iii) Equipment considered effectively grounded. Electric equipment is considered to be effectively grounded if it is secured to, and in electrical contact with, a metal rack or structure that is provided for its support and the metal rack or structure is grounded by the method specified for the noncurrent-carrying metal parts of fixed equipment in paragraph (f)(8)(i) of this section. Metal car frames supported by metal hoisting cables attached to or running over metal sheaves or drums of grounded elevator machines are also considered to be effectively grounded.
    (9) Bonding. If bonding conductors are used to assure electrical continuity, they shall have the capacity to conduct any fault current which may be imposed.
    (10) Made electrodes. If made electrodes are used, they shall be free from nonconductive coatings, such as paint or enamel; and, if practicable, they shall be embedded below permanent moisture level. A single electrode consisting of a rod, pipe or plate which has a resistance to ground greater than 25 ohms shall be augmented by one additional electrode installed no closer than 6 feet (1.83 m) to the first electrode.
    (11) Grounding of systems and circuits of 1000 volts and over (high voltage) -- (i) General. If high voltage systems are grounded, they shall comply with all applicable provisions of paragraphs (f)(1) through (f)(10) of this section as supplemented and modified by this paragraph (f)(11).
    (ii) Grounding of systems supplying portable or mobile equipment. Systems supplying portable or mobile high voltage equipment, other than substations installed on a temporary basis, shall comply with the following:
    (A) Portable and mobile high voltage equipment shall be supplied from a system having its neutral grounded through an impedance. If a delta-connected high voltage system is used to supply the equipment, a system neutral shall be derived.
    (B) Exposed noncurrent-carrying metal parts of portable and mobile equipment shall be connected by an equipment grounding conductor to the point at which the system neutral impedance is grounded.
    (C) Ground-fault detection and relaying shall be provided to automatically de-energize any high voltage system component which has developed a ground fault. The continuity of the equipment grounding conductor shall be continuously monitored so as to de-energize automatically the high voltage feeder to the portable equipment upon loss of continuity of the equipment grounding conductor.
    (D) The grounding electrode to which the portable or mobile equipment system neutral impedance is connected shall be isolated from and separated in the ground by at least 20 feet (6.1 m) from any other system or equipment grounding electrode, and there shall be no direct connection between the grounding electrodes, such as buried pipe, fence or like objects.
    (iii) Grounding of equipment. All noncurrent-carrying metal parts of portable equipment and fixed equipment including their associated fences, housings, enclosures, and supporting structures shall be grounded. However, equipment which is guarded by location and isolated from ground need not be grounded. Additionally, pole-mounted distribution apparatus at a height exceeding 8 feet (2.44 m) above ground or grade level need not be grounded.
[51 FR 25318, July 11, 1986, as amended at 54 FR 24334, June 7, 1989; 61 FR 5510, Feb. 13, 1996]
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§1926.405   Wiring methods, components, and equipment for general use.
    (a) Wiring methods. The provisions of this paragraph do not apply to conductors which form an integral part of equipment such as motors, controllers, motor control centers and like equipment.
    (1) General requirements -- (i) Electrical continuity of metal raceways and enclosures. Metal raceways, cable armor, and other metal enclosures for conductors shall be metallically joined together into a continuous electric conductor and shall be so connected to all boxes, fittings, and cabinets as to provide effective electrical continuity.
    (ii) Wiring in ducts. No wiring systems of any type shall be installed in ducts used to transport dust, loose stock or flammable vapors. No wiring system of any type shall be installed in any duct used for vapor removal or in any shaft containing only such ducts.
    (2) Temporary wiring -- (i) Scope. The provisions of paragraph (a)(2) of this section apply to temporary electrical power and lighting wiring methods which may be of a class less than would be required for a permanent installation. Except as specifically modified in paragraph (a)(2) of this section, all other requirements of this subpart for permanent wiring shall apply to temporary wiring installations. Temporary wiring shall be removed immediately upon completion of construction or the purpose for which the wiring was installed.
    (ii) General requirements for temporary wiring -- (A) Feeders shall originate in a distribution center. The conductors shall be run as multiconductor cord or cable assemblies or within raceways; or, where not subject to physical damage, they may be run as open conductors on insulators not more than 10 feet (3.05 m) apart.
    (B) Branch circuits shall originate in a power outlet or panelboard. Conductors shall be run as multiconductor cord or cable assemblies or open conductors, or shall be run in raceways. All conductors shall be protected by overcurrent devices at their ampacity. Runs of open conductors shall be located where the conductors will not be subject to physical damage, and the conductors shall be fastened at intervals not exceeding 10 feet (3.05 m). No branch-circuit conductors shall be laid on the floor. Each branch circuit that supplies receptacles or fixed equipment shall contain a separate equipment grounding conductor if the branch circuit is run as open conductors.
    (C) Receptacles shall be of the grounding type. Unless installed in a complete metallic raceway, each branch circuit shall contain a separate equipment grounding conductor, and all receptacles shall be electrically connected to the grounding conductor. Receptacles for uses other than temporary lighting shall not be installed on branch circuits which supply temporary lighting. Receptacles shall not be connected to the same ungrounded conductor of multiwire circuits which supply temporary lighting.
    (D) Disconnecting switches or plug connectors shall be installed to permit the disconnection of all ungrounded conductors of each temporary circuit.
    (E) All lamps for general illumination shall be protected from accidental contact or breakage. Metal-case sockets shall be grounded.
    (F) Temporary lights shall not be suspended by their electric cords unless cords and lights are designed for this means of suspension.
    (G) Portable electric lighting used in wet and/or other conductive locations, as for example, drums, tanks, and vessels, shall be operated at 12 volts or less. However, 120-volt lights may be used if protected by a ground-fault circuit interrupter.
    (H) A box shall be used wherever a change is made to a raceway system or a cable system which is metal clad or metal sheathed.
    (I) Flexible cords and cables shall be protected from damage. Sharp corners and projections shall be avoided. Flexible cords and cables may pass through doorways or other pinch points, if protection is provided to avoid damage.
    (J) Extension cord sets used with portable electric tools and appliances shall be of three-wire type and shall be designed for hard or extra-hard usage. Flexible cords used with temporary and portable lights shall be designed for hard or extra-hard usage.
    Note: The National Electrical Code, ANSI/NFPA 70, in Article 400, Table 400-4, lists various types of flexible cords, some of which are noted as being designed for hard or extra-hard usage. Examples of these types of flexible cords include hard service cord (types S, ST, SO, STO) and junior hard service cord (types SJ, SJO, SJT, SJTO).
    (iii) Guarding. For temporary wiring over 600 volts, nominal, fencing, barriers, or other effective means shall be provided to prevent access of other than authorized and qualified personnel.
    (b) Cabinets, boxes, and fittings -- (1) Conductors entering boxes, cabinets, or fittings. Conductors entering boxes, cabinets, or fittings shall be protected from abrasion, and openings through which conductors enter shall be effectively closed. Unused openings in cabinets, boxes, and fittings shall also be effectively closed.
    (2) Covers and canopies. All pull boxes, junction boxes, and fittings shall be provided with covers. If metal covers are used, they shall be grounded. In energized installations each outlet box shall have a cover, faceplate, or fixture canopy. Covers of outlet boxes having holes through which flexible cord pendants pass shall be provided with bushings designed for the purpose or shall have smooth, well-rounded surfaces on which the cords may bear.
    (3) Pull and junction boxes for systems over 600 volts, nominal. In addition to other requirements in this section for pull and junction boxes, the following shall apply to these boxes for systems over 600 volts, nominal:
    (i) Complete enclosure. Boxes shall provide a complete enclosure for the contained conductors or cables.
    (ii) Covers. Boxes shall be closed by covers securely fastened in place. Underground box covers that weigh over 100 pounds (43.6 kg) meet this requirement. Covers for boxes shall be permanently marked "HIGH VOLTAGE." The marking shall be on the outside of the box cover and shall be readily visible and legible.
    (c) Knife switches. Single-throw knife switches shall be so connected that the blades are dead when the switch is in the open position. Single-throw knife switches shall be so placed that gravity will not tend to close them. Single-throw knife switches approved for use in the inverted position shall be provided with a locking device that will ensure that the blades remain in the open position when so set. Double-throw knife switches may be mounted so that the throw will be either vertical or horizontal. However, if the throw is vertical, a locking device shall be provided to ensure that the blades remain in the open position when so set.
    (d) Switchboards and panelboards. Switchboards that have any exposed live parts shall be located in permanently dry locations and accessible only to qualified persons. Panelboards shall be mounted in cabinets, cutout boxes, or enclosures designed for the purpose and shall be dead front. However, panelboards other than the dead front externally-operable type are permitted where accessible only to qualified persons. Exposed blades of knife switches shall be dead when open.
    (e) Enclosures for damp or wet locations -- (1) Cabinets, fittings, and boxes. Cabinets, cutout boxes, fittings, boxes, and panelboard enclosures in damp or wet locations shall be installed so as to prevent moisture or water from entering and accumulating within the enclosures. In wet locations the enclosures shall be weatherproof.
    (2) Switches and circuit breakers. Switches, circuit breakers, and switchboards installed in wet locations shall be enclosed in weatherproof enclosures.
    (f) Conductors for general wiring. All conductors used for general wiring shall be insulated unless otherwise permitted in this subpart. The conductor insulation shall be of a type that is suitable for the voltage, operating temperature, and location of use. Insulated conductors shall be distinguishable by appropriate color or other means as being grounded conductors, ungrounded conductors, or equipment grounding conductors.
    (g) Flexible cords and cables -- (1) Use of flexible cords and cables -- (i) Permitted uses. Flexible cords and cables shall be suitable for conditions of use and location. Flexible cords and cables shall be used only for:
    (A) Pendants;
    (B) Wiring of fixtures;
    (C) Connection of portable lamps or appliances;
    (D) Elevator cables;
    (E) Wiring of cranes and hoists;
    (F) Connection of stationary equipment to facilitate their frequent interchange;
    (G) Prevention of the transmission of noise or vibration; or
    (H) Appliances where the fastening means and mechanical connections are designed to permit removal for maintenance and repair.
    (ii) Attachment plugs for cords. If used as permitted in paragraphs (g)(1)(i)(C), (g)(1)(i)(F), or (g)(1)(i)(H) of this section, the flexible cord shall be equipped with an attachment plug and shall be energized from a receptacle outlet.
    (iii) Prohibited uses. Unless necessary for a use permitted in paragraph (g)(1)(i) of this section, flexible cords and cables shall not be used:
    (A) As a substitute for the fixed wiring of a structure;
    (B) Where run through holes in walls, ceilings, or floors;
    (C) Where run through doorways, windows, or similar openings, except as permitted in paragraph (a)(2)(ii)(I) of this section;
    (D) Where attached to building surfaces; or
    (E) Where concealed behind building walls, ceilings, or floors.
    (2) Identification, splices, and terminations -- (i) Identification. A conductor of a flexible cord or cable that is used as a grounded conductor or an equipment grounding conductor shall be distinguishable from other conductors.
    (ii) Marking. Type SJ, SJO, SJT, SJTO, S, SO, ST, and STO cords shall not be used unless durably marked on the surface with the type designation, size, and number of conductors.
    (iii) Splices. Flexible cords shall be used only in continuous lengths without splice or tap. Hard service flexible cords No. 12 or larger may be repaired if spliced so that the splice retains the insulation, outer sheath properties, and usage characteristics of the cord being spliced.
    (iv) Strain relief. Flexible cords shall be connected to devices and fittings so that strain relief is provided which will prevent pull from being directly transmitted to joints or terminal screws.
    (v) Cords passing through holes. Flexible cords and cables shall be protected by bushings or fittings where passing through holes in covers, outlet boxes, or similar enclosures.
    (h) Portable cables over 600 volts, nominal. Multiconductor portable cable for use in supplying power to portable or mobile equipment at over 600 volts, nominal, shall consist of No. 8 or larger conductors employing flexible stranding. Cables operated at over 2000 volts shall be shielded for the purpose of confining the voltage stresses to the insulation. Grounding conductors shall be provided. Connectors for these cables shall be of a locking type with provisions to prevent their opening or closing while energized. Strain relief shall be provided at connections and terminations. Portable cables shall not be operated with splices unless the splices are of the permanent molded, vulcanized, or other equivalent type. Termination enclosures shall be marked with a high voltage hazard warning, and terminations shall be accessible only to authorized and qualified personnel.
    (i) Fixture wires -- (1) General. Fixture wires shall be suitable for the voltage, temperature, and location of use. A fixture wire which is used as a grounded conductor shall be identified.
    (2) Uses permitted. Fixture wires may be used:
    (i) For installation in lighting, fixtures and in similar equipment where enclosed or protected and not subject to bending or twisting in use; or
    (ii) For connecting lighting fixtures to the branch-circuit conductors supplying the fixtures.
    (3) Uses not permitted. Fixture wires shall not be used as branch-circuit conductors except as permitted for Class 1 power-limited circuits.
    (j) Equipment for general use -- (1) Lighting fixtures, lampholders, lamps, and receptacles -- (i) Live parts. Fixtures, lampholders, lamps, rosettes, and receptacles shall have no live parts normally exposed to employee contact. However, rosettes and cleat-type lampholders and receptacles located at least 8 feet (2.44 m) above the floor may have exposed parts.
    (ii) Support. Fixtures, lampholders, rosettes, and receptacles shall be securely supported. A fixture that weighs more than 6 pounds (2.72 kg) or exceeds 16 inches (406 mm) in any dimension shall not be supported by the screw shell of a lampholder.
    (iii) Portable lamps. Portable lamps shall be wired with flexible cord and an attachment plug of the polarized or grounding type. If the portable lamp uses an Edison-based lampholder, the grounded conductor shall be identified and attached to the screw shell and the identified blade of the attachment plug. In addition, portable handlamps shall comply with the following:
    (A) Metal shell, paperlined lampholders shall not be used;
    (B) Handlamps shall be equipped with a handle of molded composition or other insulating material;
    (C) Handlamps shall be equipped with a substantial guard attached to the lampholder or handle;
    (D) Metallic guards shall be grounded by the means of an equipment grounding conductor run within the power supply cord.
    (iv) Lampholders. Lampholders of the screw-shell type shall be installed for use as lampholders only. Lampholders installed in wet or damp locations shall be of the weatherproof type.
    (v) Fixtures. Fixtures installed in wet or damp locations shall be identified for the purpose and shall be installed so that water cannot enter or accumulate in wireways, lampholders, or other electrical parts.
    (2) Receptacles, cord connectors, and attachment plugs (caps) -- (i) Configuration. Receptacles, cord connectors, and attachment plugs shall be constructed so that no receptacle or cord connector will accept an attachment plug with a different voltage or current rating than that for which the device is intended. However, a 20-ampere T-slot receptacle or cord connector may accept a 15-ampere attachment plug of the same voltage rating. Receptacles connected to circuits having different voltages, frequencies, or types of current (ac or dc) on the same premises shall be of such design that the attachment plugs used on these circuits are not interchangeable.
    (ii) Damp and wet locations. A receptacle installed in a wet or damp location shall be designed for the location.
    (3) Appliances -- (i) Live parts. Appliances, other than those in which the current-carrying parts at high temperatures are necessarily exposed, shall have no live parts normally exposed to employee contact.
    (ii) Disconnecting means. A means shall be provided to disconnect each appliance.
    (iii) Rating. Each appliance shall be marked with its rating in volts and amperes or volts and watts.
    (4) Motors. This paragraph applies to motors, motor circuits, and controllers.
    (i) In sight from. If specified that one piece of equipment shall be "in sight from" another piece of equipment, one shall be visible and not more than 50 feet (15.2 m) from the other.
    (ii) Disconnecting means -- (A) A disconnecting means shall be located in sight from the controller location. The controller disconnecting means for motor branch circuits over 600 volts, nominal, may be out of sight of the controller, if the controller is marked with a warning label giving the location and identification of the disconnecting means which is to be locked in the open position.
    (B) The disconnecting means shall disconnect the motor and the controller from all ungrounded supply conductors and shall be so designed that no pole can be operated independently.
    (C) If a motor and the driven machinery are not in sight from the controller location, the installation shall comply with one of the following conditions:
    (1) The controller disconnecting means shall be capable of being locked in the open position.
    (2) A manually operable switch that will disconnect the motor from its source of supply shall be placed in sight from the motor location.
    (D) The disconnecting means shall plainly indicate whether it is in the open (off) or closed (on) position.
    (E) The disconnecting means shall be readily accessible. If more than one disconnect is provided for the same equipment, only one need be readily accessible.
    (F) An individual disconnecting means shall be provided for each motor, but a single disconnecting means may be used for a group of motors under any one of the following conditions:
    (1) If a number of motors drive special parts of a single machine or piece of apparatus, such as a metal or woodworking machine, crane, or hoist;
    (2) If a group of motors is under the protection of one set of branch-circuit protective devices; or
    (3) If a group of motors is in a single room in sight from the location of the disconnecting means.
    (iii) Motor overload, short-circuit, and ground-fault protection. Motors, motor-control apparatus, and motor branch-circuit conductors shall be protected against overheating due to motor overloads or failure to start, and against short-circuits or ground faults. These provisions do not require overload protection that will stop a motor where a shutdown is likely to introduce additional or increased hazards, as in the case of fire pumps, or where continued operation of a motor is necessary for a safe shutdown of equipment or process and motor overload sensing devices are connected to a supervised alarm.
    (iv) Protection of live parts -- all voltages -- (A) Stationary motors having commutators, collectors, and brush rigging located inside of motor end brackets and not conductively connected to supply circuits operating at more than 150 volts to ground need not have such parts guarded. Exposed live parts of motors and controllers operating at 50 volts or more between terminals shall be guarded against accidental contact by any of the following:
    (1) By installation in a room or enclosure that is accessible only to qualified persons;
    (2) By installation on a balcony, gallery, or platform, so elevated and arranged as to exclude unqualified persons; or
    (3) By elevation 8 feet (2.44 m) or more above the floor.
    (B) Where live parts of motors or controllers operating at over 150 volts to ground are guarded against accidental contact only by location, and where adjustment or other attendance may be necessary during the operation of the apparatus, insulating mats or platforms shall be provided so that the attendant cannot readily touch live parts unless standing on the mats or platforms.
    (5) Transformers -- (i) Application. The following paragraphs cover the installation of all transformers, except:
    (A) Current transformers;
    (B) Dry-type transformers installed as a component part of other apparatus;
    (C) Transformers which are an integral part of an X-ray, high frequency, or electrostatic-coating apparatus;
    (D) Transformers used with Class 2 and Class 3 circuits, sign and outline lighting, electric discharge lighting, and power-limited fire-protective signaling circuits.
    (ii) Operating voltage. The operating voltage of exposed live parts of transformer installations shall be indicated by warning signs or visible markings on the equipment or structure.
    (iii) Transformers over 35 kV. Dry-type, high fire point liquid-insulated, and askarel-insulated transformers installed indoors and rated over 35 kV shall be in a vault.
    (iv) Oil-insulated transformers. If they present a fire hazard to employees, oil-insulated transformers installed indoors shall be in a vault.
    (v) Fire protection. Combustible material, combustible buildings and parts of buildings, fire escapes, and door and window openings shall be safeguarded from fires which may originate in oil-insulated transformers attached to or adjacent to a building or combustible material.
    (vi) Transformer vaults. Transformer vaults shall be constructed so as to contain fire and combustible liquids within the vault and to prevent unauthorized access. Locks and latches shall be so arranged that a vault door can be readily opened from the inside.
    (vii) Pipes and ducts. Any pipe or duct system foreign to the vault installation shall not enter or pass through a transformer vault.
    (viii) Material storage. Materials shall not be stored in transformer vaults.
    (6) Capacitors -- (i) Drainage of stored charge. All capacitors, except surge capacitors or capacitors included as a component part of other apparatus, shall be provided with an automatic means of draining the stored charge and maintaining the discharged state after the capacitor is disconnected from its source of supply.
    (ii) Over 600 volts. Capacitors rated over 600 volts, nominal, shall comply with the following additional requirements:
    (A) Isolating or disconnecting switches (with no interrupting rating) shall be interlocked with the load interrupting device or shall be provided with prominently displayed caution signs to prevent switching load current.
    (B) For series capacitors the proper switching shall be assured by use of at least one of the following:
    (1) Mechanically sequenced isolating and bypass switches,
    (2) Interlocks, or
    (3) Switching procedure prominently displayed at the switching location.
[51 FR 25318, July 11, 1986, as amended at 61 FR 5510, Feb. 13, 1996; 85 FR 8736, Feb. 18, 2020]
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§1926.406   Specific purpose equipment and installations.
    (a) Cranes and hoists. This paragraph applies to the installation of electric equipment and wiring used in connection with cranes, monorail hoists, hoists, and all runways.
    (1) Disconnecting means -- (i) Runway conductor disconnecting means. A readily accessible disconnecting means shall be provided between the runway contact conductors and the power supply.
    (ii) Disconnecting means for cranes and monorail hoists. A disconnecting means, capable of being locked in the open position, shall be provided in the leads from the runway contact conductors or other power supply on any crane or monorail hoist.
    (A) If this additional disconnecting means is not readily accessible from the crane or monorail hoist operating station, means shall be provided at the operating station to open the power circuit to all motors of the crane or monorail hoist.
    (B) The additional disconnect may be omitted if a monorail hoist or hand-propelled crane bridge installation meets all of the following:
    (1) The unit is floor controlled;
    (2) The unit is within view of the power supply disconnecting means; and
    (3) No fixed work platform has been provided for servicing the unit.
    (2) Control. A limit switch or other device shall be provided to prevent the load block from passing the safe upper limit of travel of any hoisting mechanism.
    (3) Clearance. The dimension of the working space in the direction of access to live parts which may require examination, adjustment, servicing, or maintenance while alive shall be a minimum of 2 feet 6 inches (762 mm). Where controls are enclosed in cabinets, the door(s) shall open at least 90 degrees or be removable, or the installation shall provide equivalent access.
    (4) Grounding. All exposed metal parts of cranes, monorail hoists, hoists and accessories including pendant controls shall be metallically joined together into a continuous electrical conductor so that the entire crane or hoist will be grounded in accordance with §1926.404(f). Moving parts, other than removable accessories or attachments, having metal-to-metal bearing surfaces shall be considered to be electrically connected to each other through the bearing surfaces for grounding purposes. The trolley frame and bridge frame shall be considered as electrically grounded through the bridge and trolley wheels and its respective tracks unless conditions such as paint or other insulating materials prevent reliable metal-to-metal contact. In this case a separate bonding conductor shall be provided.
    (b) Elevators, escalators, and moving walks -- (1) Disconnecting means. Elevators, escalators, and moving walks shall have a single means for disconnecting all ungrounded main power supply conductors for each unit.
    (2) Control panels. If control panels are not located in the same space as the drive machine, they shall be located in cabinets with doors or panels capable of being locked closed.
    (c) Electric welders -- disconnecting means -- (1) Motor-generator, AC transformer, and DC rectifier arc welders. A disconnecting means shall be provided in the supply circuit for each motor-generator arc welder, and for each AC transformer and DC rectifier arc welder which is not equipped with a disconnect mounted as an integral part of the welder.
    (2) Resistance welders. A switch or circuit breaker shall be provided by which each resistance welder and its control equipment can be isolated from the supply circuit. The ampere rating of this disconnecting means shall not be less than the supply conductor ampacity.
    (d) X-Ray equipment -- (1) Disconnecting means -- (i) General. A disconnecting means shall be provided in the supply circuit. The disconnecting means shall be operable from a location readily accessible from the X-ray control. For equipment connected to a 120-volt branch circuit of 30 amperes or less, a grounding-type attachment plug cap and receptacle of proper rating may serve as a disconnecting means.
    (ii) More than one piece of equipment. If more than one piece of equipment is operated from the same high-voltage circuit, each piece or each group of equipment as a unit shall be provided with a high-voltage switch or equivalent disconnecting means. This disconnecting means shall be constructed, enclosed, or located so as to avoid contact by employees with its live parts.
    (2) Control -- Radiographic and fluoroscopic types. Radiographic and fluoroscopic-type equipment shall be effectively enclosed or shall have interlocks that deenergize the equipment automatically to prevent ready access to live current-carrying parts.
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§1926.407   Hazardous (classified) locations.
    (a) Scope. This section sets forth requirements for electric equipment and wiring in locations which are classified depending on the properties of the flammable vapors, liquids or gases, or combustible dusts or fibers which may be present therein and the likelihood that a flammable or combustible concentration or quantity is present. Each room, section or area shall be considered individually in determining its classification. These hazardous (classified) locations are assigned six designations as follows:
  Class I, Division 1
  Class I, Division 2
  Class II, Division 1
  Class II, Division 2
  Class III, Division l
  Class III, Division 2
    For definitions of these locations see §1926.449. All applicable requirements in this subpart apply to all hazardous (classified) locations, unless modified by provisions of this section.
    (b) Electrical installations. Equipment, wiring methods, and installations of equipment in hazardous (classified) locations shall be approved as intrinsically safe or approved for the hazardous (classified) location or safe for the hazardous (classified) location. Requirements for each of these options are as follows:
    (1) Intrinsically safe. Equipment and associated wiring approved as intrinsically safe is permitted in any hazardous (classified) location included in its listing or labeling.
    (2) Approved for the hazardous (classified) location -- (i) General. Equipment shall be approved not only for the class of location but also for the ignitible or combustible properties of the specific gas, vapor, dust, or fiber that will be present.
    Note: NFPA 70, the National Electrical Code, lists or defines hazardous gases, vapors, and dusts by "Groups" characterized by their ignitible or combustible properties.
    (ii) Marking. Equipment shall not be used unless it is marked to show the class, group, and operating temperature or temperature range, based on operation in a 40-degree C ambient, for which it is approved. The temperature marking shall not exceed the ignition temperature of the specific gas, vapor, or dust to be encountered. However, the following provisions modify this marking requirement for specific equipment:
    (A) Equipment of the non-heat-producing type (such as junction boxes, conduit, and fitting) and equipment of the heat-producing type having a maximum temperature of not more than 100 degrees C (212 degrees F) need not have a marked operating temperature or temperature range.
    (B) Fixed lighting fixtures marked for use only in Class I, Division 2 locations need not be marked to indicate the group.
    (C) Fixed general-purpose equipment in Class I locations, other than lighting fixtures, which is acceptable for use in Class I, Division 2 locations need not be marked with the class, group, division, or operating temperature.
    (D) Fixed dust-tight equipment, other than lighting fixtures, which is acceptable for use in Class II, Division 2 and Class III locations need not be marked with the class, group, division, or operating temperature.
    (3) Safe for the hazardous (classified) location. Equipment which is safe for the location shall be of a type and design which the employer demonstrates will provide protection from the hazards arising from the combustibility and flammability of vapors, liquids, gases, dusts, or fibers.
    Note: The National Electrical Code, NFPA 70, contains guidelines for determining the type and design of equipment and installations which will meet this requirement. The guidelines of this document address electric wiring, equipment, and systems installed in hazardous (classified) locations and contain specific provisions for the following: wiring methods, wiring connections, conductor insulation, flexible cords, sealing and drainage, transformers, capacitors, switches, circuit breakers, fuses, motor controllers, receptacles, attachment plugs, meters, relays, instruments, resistors, generators, motors, lighting fixtures, storage battery charging equipment, electric cranes, electric hoists and similar equipment, utilization equipment, signaling systems, alarm systems, remote control systems, local loud speaker and communication systems, ventilation piping, live parts, lightning surge protection, and grounding. Compliance with these guidelines will constitute one means, but not the only means, of compliance with this paragraph.
    (c) Conduits. All conduits shall be threaded and shall be made wrench-tight. Where it is impractical to make a threaded joint tight, a bonding jumper shall be utilized.
[51 FR 25318, July 11, 1986, as amended at 61 FR 5510, Feb. 13, 1996]
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§1926.408   Special systems.
    (a) Systems over 600 volts, nominal. Paragraphs (a)(1) through (a)(4) of this section contain general requirements for all circuits and equipment operated at over 600 volts.
    (1) Wiring methods for fixed installations -- (i) Above ground. Above-ground conductors shall be installed in rigid metal conduit, in intermediate metal conduit, in cable trays, in cablebus, in other suitable raceways, or as open runs of metal-clad cable designed for the use and purpose. However, open runs of non-metallic-sheathed cable or of bare conductors or busbars may be installed in locations which are accessible only to qualified persons. Metallic shielding components, such as tapes, wires, or braids for conductors, shall be grounded. Open runs of insulated wires and cables having a bare lead sheath or a braided outer covering shall be supported in a manner designed to prevent physical damage to the braid or sheath.
    (ii) Installations emerging from the ground. Conductors emerging from the ground shall be enclosed in raceways. Raceways installed on poles shall be of rigid metal conduit, intermediate metal conduit, PVC schedule 80 or equivalent extending from the ground line up to a point 8 feet (2.44 m) above finished grade. Conductors entering a building shall be protected by an enclosure from the ground line to the point of entrance. Metallic enclosures shall be grounded.
    (2) Interrupting and isolating devices -- (i) Circuit breakers. Circuit breakers located indoors shall consist of metal-enclosed or fire-resistant, cell-mounted units. In locations accessible only to qualified personnel, open mounting of circuit breakers is permitted. A means of indicating the open and closed position of circuit breakers shall be provided.
    (ii) Fused cutouts. Fused cutouts installed in buildings or transformer vaults shall be of a type identified for the purpose. They shall be readily accessible for fuse replacement.
    (iii) Equipment isolating means. A means shall be provided to completely isolate equipment for inspection and repairs. Isolating means which are not designed to interrupt the load current of the circuit shall be either interlocked with a circuit interrupter or provided with a sign warning against opening them under load.
    (3) Mobile and portable equipment -- (i) Power cable connections to mobile machines. A metallic enclosure shall be provided on the mobile machine for enclosing the terminals of the power cable. The enclosure shall include provisions for a solid connection for the ground wire(s) terminal to ground effectively the machine frame. The method of cable termination used shall prevent any strain or pull on the cable from stressing the electrical connections. The enclosure shall have provision for locking so only authorized qualified persons may open it and shall be marked with a sign warning of the presence of energized parts.
    (ii) Guarding live parts. All energized switching and control parts shall be enclosed in effectively grounded metal cabinets or enclosures. Circuit breakers and protective equipment shall have the operating means projecting through the metal cabinet or enclosure so these units can be reset without locked doors being opened. Enclosures and metal cabinets shall be locked so that only authorized qualified persons have access and shall be marked with a sign warning of the presence of energized parts. Collector ring assemblies on revolving-type machines (shovels, draglines, etc.) shall be guarded.
    (4) Tunnel installations -- (i) Application. The provisions of this paragraph apply to installation and use of high-voltage power distribution and utilization equipment which is associated with tunnels and which is portable and/or mobile, such as substations, trailers, cars, mobile shovels, draglines, hoists, drills, dredges, compressors, pumps, conveyors, and underground excavators.
    (ii) Conductors. Conductors in tunnels shall be installed in one or more of the following:
    (A) Metal conduit or other metal raceway,
    (B) Type MC cable, or
    (C) Other suitable multiconductor cable.
Conductors shall also be so located or guarded as to protect them from physical damage. Multiconductor portable cable may supply mobile equipment. An equipment grounding conductor shall be run with circuit conductors inside the metal raceway or inside the multiconductor cable jacket. The equipment grounding conductor may be insulated or bare.
    (iii) Guarding live parts. Bare terminals of transformers, switches, motor controllers, and other equipment shall be enclosed to prevent accidental contact with energized parts. Enclosures for use in tunnels shall be drip-proof, weatherproof, or submersible as required by the environmental conditions.
    (iv) Disconnecting means. A disconnecting means that simultaneously opens all ungrounded conductors shall be installed at each transformer or motor location.
    (v) Grounding and bonding. All nonenergized metal parts of electric equipment and metal raceways and cable sheaths shall be grounded and bonded to all metal pipes and rails at the portal and at intervals not exceeding 1000 feet (305 m) throughout the tunnel.
    (b) Class 1, Class 2, and Class 3 remote control, signaling, and power-limited circuits -- (1) Classification. Class 1, Class 2, or Class 3 remote control, signaling, or power-limited circuits are characterized by their usage and electrical power limitation which differentiates them from light and power circuits. These circuits are classified in accordance with their respective voltage and power limitations as summarized in paragraphs (b)(1)(i) through (b)(1)(iii) of this section.
    (i) Class 1 circuits -- (A) A Class 1 power-limited circuit is supplied from a source having a rated output of not more than 30 volts and 1000 volt-amperes.
    (B) A Class 1 remote control circuit or a Class 1 signaling circuit has a voltage which does not exceed 600 volts; however, the power output of the source need not be limited.
    (ii) Class 2 and Class 3 circuits -- (A) Power for Class 2 and Class 3 circuits is limited either inherently (in which no overcurrent protection is required) or by a combination of a power source and overcurrent protection.
    (B) The maximum circuit voltage is 150 volts AC or DC for a Class 2 inherently limited power source, and 100 volts AC or DC for a Class 3 inherently limited power source.
    (C) The maximum circuit voltage is 30 volts AC and 60 volts DC for a Class 2 power source limited by overcurrent protection, and 150 volts AC or DC for a Class 3 power source limited by overcurrent protection.
    (iii) Application. The maximum circuit voltages in paragraphs (b)(1)(i) and (b)(1)(ii) of this section apply to sinusoidal AC or continuous DC power sources, and where wet contact occurrence is not likely.
    (2) Marking. A Class 2 or Class 3 power supply unit shall not be used unless it is durably marked where plainly visible to indicate the class of supply and its electrical rating.
    (c) Communications systems -- (1) Scope. These provisions for communication systems apply to such systems as central-station-connected and non-central-station-connected telephone circuits, radio receiving and transmitting equipment, and outside wiring for fire and burglar alarm, and similar central station systems. These installations need not comply with the provisions of §§1926.403 through 1926.408(b), except §1926.404(c)(1)(ii) and §1926.407.
    (2) Protective devices -- (i) Circuits exposed to power conductors. Communication circuits so located as to be exposed to accidental contact with light or power conductors operating at over 300 volts shall have each circuit so exposed provided with an approved protector.
    (ii) Antenna lead-ins. Each conductor of a lead-in from an outdoor antenna shall be provided with an antenna discharge unit or other means that will drain static charges from the antenna system.
    (3) Conductor location -- (i) Outside of buildings -- (A) Receiving distribution lead-in or aerial-drop cables attached to buildings and lead-in conductors to radio transmitters shall be so installed as to avoid the possibility of accidental contact with electric light or power conductors.
    (B) The clearance between lead-in conductors and any lightning protection conductors shall not be less than 6 feet (1.83 m).
    (ii) On poles. Where practicable, communication conductors on poles shall be located below the light or power conductors. Communications conductors shall not be attached to a crossarm that carries light or power conductors.
    (iii) Inside of buildings. Indoor antennas, lead-ins, and other communication conductors attached as open conductors to the inside of buildings shall be located at least 2 inches (50.8 mm) from conductors of any light or power or Class 1 circuits unless a special and equally protective method of conductor separation is employed.
    (4) Equipment location. Outdoor metal structures supporting antennas, as well as self-supporting antennas such as vertical rods or dipole structures, shall be located as far away from overhead conductors of electric light and power circuits of over 150 volts to ground as necessary to avoid the possibility of the antenna or structure falling into or making accidental contact with such circuits.
    (5) Grounding -- (i) Lead-in conductors. If exposed to contact with electric light or power conductors, the metal sheath of aerial cables entering buildings shall be grounded or shall be interrupted close to the entrance to the building by an insulating joint or equivalent device. Where protective devices are used, they shall be grounded.
    (ii) Antenna structures. Masts and metal structures supporting antennas shall be permanently and effectively grounded without splice or connection in the grounding conductor.
    (iii) Equipment enclosures. Transmitters shall be enclosed in a metal frame or grill or separated from the operating space by a barrier, all metallic parts of which are effectively connected to ground. All external metal handles and controls accessible to the operating personnel shall be effectively grounded. Unpowered equipment and enclosures shall be considered grounded where connected to an attached coaxial cable with an effectively grounded metallic shield.
[51 FR 25318, July 11, 1986, as amended at 61 FR 5510, Feb. 13, 1996]
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§§1926.409-1926.415   [Reserved]
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Safety-Related Work Practices
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§1926.416   General requirements.
    (a) Protection of employees -- (1) No employer shall permit an employee to work in such proximity to any part of an electric power circuit that the employee could contact the electric power circuit in the course of work, unless the employee is protected against electric shock by deenergizing the circuit and grounding it or by guarding it effectively by insulation or other means.
    (2) In work areas where the exact location of underground electric powerlines is unknown, employees using jack-hammers, bars, or other hand tools which may contact a line shall be provided with insulated protective gloves.
    (3) Before work is begun the employer shall ascertain by inquiry or direct observation, or by instruments, whether any part of an energized electric power circuit, exposed or concealed, is so located that the performance of the work may bring any person, tool, or machine into physical or electrical contact with the electric power circuit. The employer shall post and maintain proper warning signs where such a circuit exists. The employer shall advise employees of the location of such lines, the hazards involved, and the protective measures to be taken.
    (b) Passageways and open spaces -- -(1) Barriers or other means of guarding shall be provided to ensure that workspace for electrical equipment will not be used as a passageway during periods when energized parts of electrical equipment are exposed.
    (2) Working spaces, walkways, and similar locations shall be kept clear of cords so as not to create a hazard to employees.
    (c) Load ratings. In existing installations, no changes in circuit protection shall be made to increase the load in excess of the load rating of the circuit wiring.
    (d) Fuses. When fuses are installed or removed with one or both terminals energized, special tools insulated for the voltage shall be used.
    (e) Cords and cables. (1) Worn or frayed electric cords or cables shall not be used.
    (2) Extension cords shall not be fastened with staples, hung from nails, or suspended by wire.
[44 FR 8577, Feb. 9, 1979; 44 FR 20940, Apr. 6, 1979, as amended at 55 FR 42328, Oct. 18, 1990; 58 FR 35179, June 30, 1993; 61 FR 9251, Mar. 7, 1996; 61 FR 41738, Aug. 12, 1996]
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§1926.417   Lockout and tagging of circuits.
    (a) Controls. Controls that are to be deactivated during the course of work on energized or deenergized equipment or circuits shall be tagged.
    (b) Equipment and circuits. Equipment or circuits that are deenergized shall be rendered inoperative and shall have tags attached at all points where such equipment or circuits can be energized.
    (c) Tags. Tags shall be placed to identify plainly the equipment or circuits being worked on.
[44 FR 8577, Feb. 9, 1979; 44 FR 20940, Apr. 6, 1979, as amended at 55 FR 42328, Oct. 18, 1990; 58 FR 35181, June 30, 1993; 61 FR 9251, Mar. 7, 1996; 61 FR 41739, Aug. 12, 1996]]
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§§1926.418-1926.430   [Reserved]
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Safety-Related Maintenance and Environmental Considerations
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§1926.431   Maintenance of equipment.
    The employer shall ensure that all wiring components and utilization equipment in hazardous locations are maintained in a dust-tight, dust-ignition-proof, or explosion-proof condition, as appropriate. There shall be no loose or missing screws, gaskets, threaded connections, seals, or other impairments to a tight condition.
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§1926.432   Environmental deterioration of equipment.
    (a) Deteriorating agents -- (1) Unless identified for use in the operating environment, no conductors or equipment shall be located:
    (i) In damp or wet locations;
    (ii) Where exposed to gases, fumes, vapors, liquids, or other agents having a deteriorating effect on the conductors or equipment; or
    (iii) Where exposed to excessive temperatures.
    (2) Control equipment, utilization equipment, and busways approved for use in dry locations only shall be protected against damage from the weather during building construction.
    (b) Protection against corrosion. Metal raceways, cable armor, boxes, cable sheathing, cabinets, elbows, couplings, fittings, supports, and support hardware shall be of materials appropriate for the environment in which they are to be installed.
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§§1926.433-1926.440   [Reserved]
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Safety Requirements for Special Equipment
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§1926.441   Batteries and battery charging.
    (a) General requirements -- (1) Batteries of the unsealed type shall be located in enclosures with outside vents or in well ventilated rooms and shall be arranged so as to prevent the escape of fumes, gases, or electrolyte spray into other areas.
    (2) Ventilation shall be provided to ensure diffusion of the gases from the battery and to prevent the accumulation of an explosive mixture.
    (3) Racks and trays shall be substantial and shall be treated to make them resistant to the electrolyte.
    (4) Floors shall be of acid resistant construction unless protected from acid accumulations.
    (5) Face shields, aprons, and rubber gloves shall be provided for workers handling acids or batteries.
    (6) Facilities for quick drenching of the eyes and body shall be provided within 25 feet (7.62 m) of battery handling areas.
    (7) Facilities shall be provided for flushing and neutralizing spilled electrolyte and for fire protection.
    (b) Charging -- (1) Battery charging installations shall be located in areas designated for that purpose.
    (2) Charging apparatus shall be protected from damage by trucks.
    (3) When batteries are being charged, the vent caps shall be kept in place to avoid electrolyte spray. Vent caps shall be maintained in functioning condition.
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§§1926.442-1926.448   [Reserved]
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Definitions
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§1926.449   Definitions applicable to this subpart.
    The definitions given in this section apply to the terms used in subpart K. The definitions given here for "approved" and "qualified person" apply, instead of the definitions given in §1926.32, to the use of these terms in subpart K.
    Acceptable. An installation or equipment is acceptable to the Assistant Secretary of Labor, and approved within the meaning of this subpart K:
    (a) If it is accepted, or certified, or listed, or labeled, or otherwise determined to be safe by a qualified testing laboratory capable of determining the suitability of materials and equipment for installation and use in accordance with this standard; or
    (b) With respect to an installation or equipment of a kind which no qualified testing laboratory accepts, certifies, lists, labels, or determines to be safe, if it is inspected or tested by another Federal agency, or by a State, municipal, or other local authority responsible for enforcing occupational safety provisions of the National Electrical Code, and found in compliance with those provisions; or
    (c) With respect to custom-made equipment or related installations which are designed, fabricated for, and intended for use by a particular customer, if it is determined to be safe for its intended use by its manufacturer on the basis of test data which the employer keeps and makes available for inspection to the Assistant Secretary and his authorized representatives.
    Accepted. An installation is "accepted" if it has been inspected and found to be safe by a qualified testing laboratory.
    Accessible. (As applied to wiring methods.) Capable of being removed or exposed without damaging the building structure or finish, or not permanently closed in by the structure or finish of the building. (See "concealed" and "exposed.")
    Accessible. (As applied to equipment.) Admitting close approach; not guarded by locked doors, elevation, or other effective means. (See"Readily accessible.")
    Ampacity. The current in amperes a conductor can carry continuously under the conditions of use without exceeding its temperature rating.
    Appliances. Utilization equipment, generally other than industrial, normally built in standardized sizes or types, which is installed or connecetcd as a unit to perform one or more functions.
    Approved. Acceptable to the authority enforcing this subpart. The authority enforcing this subpart is the Assistant Secretary of Labor for Occupational Safety and Health. The definition of "acceptable" indicates what is acceptable to the Assistant Secretary of Labor, and therefore approved within the meaning of this subpart.
    Askarel. A generic term for a group of nonflammable synthetic chlorinated hydrocarbons used as electrical insulating media. Askarels of various compositional types are used. Under arcing conditions the gases produced, while consisting predominantly of noncombustible hydrogen chloride, can include varying amounts of combustible gases depending upon the askarel type.
    Attachment plug (Plug cap)(Cap). A device which, by insertion in a receptacle, establishes connection between the conductors of the attached flexible cord and the conductors connected permanently to the receptacle.
    Automatic. Self-acting, operating by its own mechanism when actuated by some impersonal influence, as for example, a change in current strength, pressure, temperature, or mechanical configuration.
    Bare conductor. See "Conductor."
    Bonding. The permanent joining of metallic parts to form an electrically conductive path which will assure electrical continuity and the capacity to conduct safely any current likely to be imposed.
    Bonding jumper. A reliable conductor to assure the required electrical conductivity between metal parts required to be electrically connected.
    Branch circuit. The circuit conductors between the final overcurrent device protecting the circuit and the outlet(s).
    Building. A structure which stands alone or which is cut off from adjoining structures by fire walls with all openings therein protected by approved fire doors.
    Cabinet. An enclosure designed either for surface or flush mounting, and provided with a frame, mat, or trim in which a swinging door or doors are or may be hung.
    Certified. Equipment is "certified" if it:
    (a) Has been tested and found by a qualified testing laboratory to meet applicable test standards or to be safe for use in a specified manner, and
    (b) Is of a kind whose production is periodically inspected by a qualified testing laboratory. Certified equipment must bear a label, tag, or other record of certification.
    Circuit breaker -- (a) (600 volts nominal, or less.) A device designed to open and close a circuit by nonautomatic means and to open the circuit automatically on a predetermined overcurrent without injury to itself when properly applied within its rating.
    (b) (Over 600 volts, nominal.) A switching device capable of making, carrying, and breaking currents under normal circuit conditions, and also making, carrying for a specified time, and breaking currents under specified abnormal circuit conditions, such as those of short circuit.
    Class I locations. Class I locations are those in which flammable gases or vapors are or may be present in the air in quantities sufficient to produce explosive or ignitible mixtures. Class I locations include the following:
    (a) Class I, Division 1. A Class I, Division 1 location is a location:
    (1) In which ignitible concentrations of flammable gases or vapors may exist under normal operating conditions; or
    (2) In which ignitible concentrations of such gases or vapors may exist frequently because of repair or maintenance operations or because of leakage; or
    (3) In which breakdown or faulty operation of equipment or processes might release ignitible concentrations of flammable gases or vapors, and might also cause simultaneous failure of electric equipment.
    Note: This classification usually includes locations where volatile flammable liquids or liquefied flammable gases are transferred from one container to another; interiors of spray booths and areas in the vicinity of spraying and painting operations where volatile flammable solvents are used; locations containing open tanks or vats of volatile flammable liquids; drying rooms or compartments for the evaporation of flammable solvents; inadequately ventilated pump rooms for flammable gas or for volatile flammable liquids; and all other locations where ignitible concentrations of flammable vapors or gases are likely to occur in the course of normal operations.
    (b) Class I, Division 2. A Class I, Division 2 location is a location:
    (1) In which volatile flammable liquids or flammable gases are handled, processed, or used, but in which the hazardous liquids, vapors, or gases will normally be confined within closed containers or closed systems from which they can escape only in case of accidental rupture or breakdown of such containers or systems, or in case of abnormal operation of equipment; or
    (2) In which ignitible concentrations of gases or vapors are normally prevented by positive mechanical ventilation, and which might become hazardous through failure or abnormal operations of the ventilating equipment; or
    (3) That is adjacent to a Class I, Division 1 location, and to which ignitible concentrations of gases or vapors might occasionally be communicated unless such communication is prevented by adequate positive-pressure ventilation from a source of clean air, and effective safeguards against ventilation failure are provided.
    Note: This classification usually includes locations where volatile flammable liquids or flammable gases or vapors are used, but which would become hazardous only in case of an accident or of some unusual operating condition. The quantity of flammable material that might escape in case of accident, the adequacy of ventilating equipment, the total area involved, and the record of the industry or business with respect to explosions or fires are all factors that merit consideration in determining the classification and extent of each location.
    Piping without valves, checks, meters, and similar devices would not ordinarily introduce a hazardous condition even though used for flammable liquids or gases. Locations used for the storage of flammable liquids or of liquefied or compressed gases in sealed containers would not normally be considered hazardous unless also subject to other hazardous conditions.
    Electrical conduits and their associated enclosures separated from process fluids by a single seal or barrier are classed as a Division 2 location if the outside of the conduit and enclosures is a nonhazardous location.
    Class II locations. Class II locations are those that are hazardous because of the presence of combustible dust. Class II locations include the following:
    (a) Class II, Division 1. A Class II, Division 1 location is a location:
    (1) In which combustible dust is or may be in suspension in the air under normal operating conditions, in quantities sufficient to produce explosive or ignitible mixtures; or
    (2) Where mechanical failure or abnormal operation of machinery or equipment might cause such explosive or ignitible mixtures to be produced, and might also provide a source of ignition through simultaneous failure of electric equipment, operation of protection devices, or from other causes, or
    (3) In which combustible dusts of an electrically conductive nature may be present.
    Note: Combustible dusts which are electrically nonconductive include dusts produced in the handling and processing of grain and grain products, pulverized sugar and cocoa, dried egg and milk powders, pulverized spices, starch and pastes, potato and woodflour, oil meal from beans and seed, dried hay, and other organic materials which may produce combustible dusts when processed or handled. Dusts containing magnesium or aluminum are particularly hazardous and the use of extreme caution is necessary to avoid ignition and explosion.
    (b) Class II, Division 2. A Class II, Division 2 location is a location in which:
    (1) Combustible dust will not normally be in suspension in the air in quantities sufficient to produce explosive or ignitible mixtures, and dust accumulations are normally insufficient to interfere with the normal operation of electrical equipment or other apparatus; or
    (2) Dust may be in suspension in the air as a result of infrequent malfunctioning of handling or processing equipment, and dust accumulations resulting therefrom may be ignitible by abnormal operation or failure of electrical equipment or other apparatus.
    Note: This classification includes locations where dangerous concentrations of suspended dust would not be likely but where dust accumulations might form on or in the vicinity of electric equipment. These areas may contain equipment from which appreciable quantities of dust would escape under abnormal operating conditions or be adjacent to a Class II Division 1 location, as described above, into which an explosive or ignitible concentration of dust may be put into suspension under abnormal operating conditions.
    Class III locations. Class III locations are those that are hazardous because of the presence of easily ignitible fibers or flyings but in which such fibers or flyings are not likely to be in suspension in the air in quantities sufficient to produce ignitible mixtures. Class 111 locations include the following:
    (a) Class III, Division 1. A Class III, Division 1 location is a location in which easily ignitible fibers or materials producing combustible flyings are handled, manufactured, or used.
    Note: Easily ignitible fibers and flyings include rayon, cotton (including cotton linters and cotton waste), sisal or henequen, istle, jute, hemp, tow, cocoa fiber, oakum, baled waste kapok, Spanish moss, excelsior, sawdust, woodchips, and other material of similar nature.
    (b) Class III, Division 2. A Class III, Division 2 location is a location in which easily ignitible fibers are stored or handled, except in process of manufacture.
    Collector ring. A collector ring is an assembly of slip rings for transferring electrical energy from a stationary to a rotating member.
    Concealed. Rendered inaccessible by the structure or finish of the building. Wires in concealed raceways are considered concealed, even though they may become accessible by withdrawing them. [See "Accessible. (As applied to wiring methods.)"]
    Conductor -- (a) Bare. A conductor having no covering or electrical insulation whatsoever.
    (b) Covered. A conductor encased within material of composition or thickness that is not recognized as electrical insulation.
    (c) Insulated. A conductor encased within material of composition and thickness that is recognized as electrical insulation.
    Controller. A device or group of devices that serves to govern, in some predetermined manner, the electric power delivered to the apparatus to which it is connected.
    Covered conductor. See "Conductor."
    Cutout. (Over 600 volts, nominal.) An assembly of a fuse support with either a fuseholder, fuse carrier, or disconnecting blade. The fuseholder or fuse carrier may include a conducting element (fuse link), or may act as the disconnecting blade by the inclusion of a nonfusible member.
    Cutout box. An enclosure designed for surface mounting and having swinging doors or covers secured directly to and telescoping with the walls of the box proper. (See "Cabinet.")
    Damp location. See "Location."
    Dead front. Without live parts exposed to a person on the operating side of the equipment.
    Device. A unit of an electrical system which is intended to carry but not utilize electric energy.
    Disconnecting means. A device, or group of devices, or other means by which the conductors of a circuit can be disconnected from their source of supply.
    Disconnecting (or Isolating) switch. (Over 600 volts, nominal.) A mechanical switching device used for isolating a circuit or equipment from a source of power.
    Dry location. See "Location."
    Enclosed. Surrounded by a case, housing, fence or walls which will prevent persons from accidentally contacting energized parts.
    Enclosure. The case or housing of apparatus, or the fence or walls surrounding an installation to prevent personnel from accidentally contacting energized parts, or to protect the equipment from physical damage.
    Equipment. A general term including material, fittings, devices, appliances, fixtures, apparatus, and the like, used as a part of, or in connection with, an electrical installation.
    Equipment grounding conductor. See "Grounding conductor, equipment."
    Explosion-proof apparatus. Apparatus enclosed in a case that is capable of withstanding an explosion of a specified gas or vapor which may occur within it and of preventing the ignition of a specified gas or vapor surrounding the enclosure by sparks, flashes, or explosion of the gas or vapor within, and which operates at such an external temperature that it will not ignite a surrounding flammable atmosphere.
    Exposed. (As applied to live parts.) Capable of being inadvertently touched or approached nearer than a safe distance by a person. It is applied to parts not suitably guarded, isolated, or insulated. (See "Accessible and "Concealed.")
    Exposed. (As applied to wiring methods.) On or attached to the surface or behind panels designed to allow access. [See "Accessible. (As applied to wiring methods.)"]
    Exposed. (For the purposes of §1926.408(d), Communications systems.) Where the circuit is in such a position that in case of failure of supports or insulation, contact with another circuit may result.
    Externally operable. Capable of being operated without exposing the operator to contact with live parts.
    Feeder. All circuit conductors between the service equipment, or the generator switchboard of an isolated plant, and the final branch-circuit overcurrent device.
    Festoon lighting. A string of outdoor lights suspended between two points more than 15 feet (4.57 m) apart.
    Fitting. An accessory such as a locknut, bushing, or other part of a wiring system that is intended primarily to perform a mechanical rather than an electrical function.
    Fuse. (Over 600 volts, nominal.) An overcurrent protective device with a circuit opening fusible part that is heated and severed by the passage of overcurrent through it. A fuse comprises all the parts that form a unit capable of performing the prescribed functions. It may or may not be the complete device necessary to connect it into an electrical circuit.
    Ground. A conducting connection, whether intentional or accidental, between an electrical circuit or equipment and the earth, or to some conducting body that serves in place of the earth.
    Grounded. Connected to earth or to some conducting body that serves in place of the earth.
    Grounded, effectively (Over 600 volts, nominal.) Permanently connected to earth through a ground connection of sufficiently low impedance and having sufficient ampacity that ground fault current which may occur cannot build up to voltages dangerous to personnel.
    Grounded conductor. A system or circuit conductor that is intentionally grounded.
    Grounding conductor. A conductor used to connect equipment or the grounded circuit of a wiring system to a grounding electrode or electrodes.
    Grounding conductor, equipment. The conductor used to connect the noncurrent-carrying metal parts of equipment, raceways, and other enclosures to the system grounded conductor and/or the grounding electrode conductor at the service equipment or at the source of a separately derived system.
    Grounding electrode conductor. The conductor used to connect the grounding electrode to the equipment grounding conductor and/or to the grounded conductor of the circuit at the service equipment or at the source of a separately derived system.
    Ground-fault circuit interrupter. A device for the protection of personnel that functions to deenergize a circuit or portion thereof within an established period of time when a current to ground exceeds some predetermined value that is less than that required to operate the overcurrent protective device of the supply circuit.
    Guarded. Covered, shielded, fenced, enclosed, or otherwise protected by means of suitable covers, casings, barriers, rails, screens, mats, or platforms to remove the likelihood of approach to a point of danger or contact by persons or objects.
    Hoistway. Any shaftway, hatchway, well hole, or other vertical opening or space in which an elevator or dumbwaiter is designed to operate.
    Identified (conductors or terminals). Identified, as used in reference to a conductor or its terminal, means that such conductor or terminal can be recognized as grounded.
    Identified (for the use). Recognized as suitable for the specific purpose, function, use, environment, application, etc. where described as a requirement in this standard. Suitability of equipment for a specific purpose, environment, or application is determined by a qualified testing laboratory where such identification includes labeling or listing.
    Insulated conductor. See "Conductor."
    Interrupter switch. (Over 600 volts, nominal.) A switch capable of making, carrying, and interrupting specified currents.
    Intrinsically safe equipment and associated wiring. Equipment and associated wiring in which any spark or thermal effect, produced either normally or in specified fault conditions, is incapable, under certain prescribed test conditions, of causing ignition of a mixture of flammable or combustible material in air in its most easily ignitible concentration.
    Isolated. Not readily accessible to persons unless special means for access are used.
    Isolated power system. A system comprising an isolating transformer or its equivalent, a line isolation monitor, and its ungrounded circuit conductors.
    Labeled. Equipment or materials to which has been attached a label, symbol or other identifying mark of a qualified testing laboratory which indicates compliance with appropriate standards or performance in a specified manner.
    Lighting outlet. An outlet intended for the direct connection of a lampholder, a lighting fixture, or a pendant cord terminating in a lampholder.
    Listed. Equipment or materials included in a list published by a qualified testing laboratory whose listing states either that the equipment or material meets appropriate standards or has been tested and found suitable for use in a specified manner.
    Location -- (a) Damp location. Partially protected locations under canopies, marquees, roofed open porches, and like locations, and interior locations subject to moderate degrees of moisture, such as some basements.
    (b) Dry location. A location not normally subject to dampness or wetness. A location classified as dry may be temporarily subject to dampness or wetness, as in the case of a building under construction.
    (c) Wet location. Installations underground or in concrete slabs or masonry in direct contact with the earth, and locations subject to saturation with water or other liquids, such as locations exposed to weather and unprotected.
    Mobile X-ray. X-ray equipment mounted on a permanent base with wheels and/or casters for moving while completely assembled.
    Motor control center. An assembly of one or more enclosed sections having a common power bus and principally containing motor control units.
    Outlet. A point on the wiring system at which current is taken to supply utilization equipment.
    Overcurrent. Any current in excess of the rated current of equipment or the ampacity of a conductor. It may result from overload (see definition), short circuit, or ground fault. A current in excess of rating may be accommodated by certain equipment and conductors for a given set of conditions. Hence the rules for overcurrent protection are specific for particular situations.
    Overload. Operation of equipment in excess of normal, full load rating, or of a conductor in excess of rated ampacity which, when it persists for a sufficient length of time, would cause damage or dangerous overheating. A fault, such as a short circuit or ground fault, is not an overload. (See"Overcurrent.")
    Panelboard. A single panel or group of panel units designed for assembly in the form of a single panel; including buses, automatic overcurrent devices, and with or without switches for the control of light, heat, or power circuits; designed to be placed in a cabinet or cutout box placed in or against a wall or partition and accessible only from the front. (See "Switchboard.")
    Portable X-ray. X-ray equipment designed to be hand-carried.
    Power fuse. (Over 600 volts, nominal.) See "Fuse."
    Power outlet. An enclosed assembly which may include receptacles, circuit breakers, fuseholders, fused switches, buses and watt-hour meter mounting means; intended to serve as a means for distributing power required to operate mobile or temporarily installed equipment.
    Premises wiring system. That interior and exterior wiring, including power, lighting, control, and signal circuit wiring together with all of its associated hardware, fittings, and wiring devices, both permanently and temporarily installed, which extends from the load end of the service drop, or load end of the service lateral conductors to the outlet(s). Such wiring does not include wiring internal to appliances, fixtures, motors, controllers, motor control centers, and similar equipment.
    Qualified person. One familiar with the construction and operation of the equipment and the hazards involved.
    Qualified testing laboratory. A properly equipped and staffed testing laboratory which has capabilities for and which provides the following services:
    (a) Experimental testing for safety of specified items of equipment and materials referred to in this standard to determine compliance with appropriate test standards or performance in a specified manner;
    (b) Inspecting the run of such items of equipment and materials at factories for product evaluation to assure compliance with the test standards;
    (c) Service-value determinations through field inspections to monitor the proper use of labels on products and with authority for recall of the label in the event a hazardous product is installed;
    (d) Employing a controlled procedure for identifying the listed and/or labeled equipment or materials tested; and
    (e) Rendering creditable reports or findings that are objective and without bias of the tests and test methods employed.
    Raceway. A channel designed expressly for holding wires, cables, or busbars, with additional functions as permitted in this subpart. Raceways may be of metal or insulating material, and the term includes rigid metal conduit, rigid nonmetallic conduit, intermediate metal conduit, liquidtight flexible metal conduit, flexible metallic tubing, flexible metal conduit, electrical metallic tubing, underfloor raceways, cellular concrete floor raceways, cellular metal floor raceways, surface raceways, wireways, and busways.
    Readily accessible. Capable of being reached quickly for operation, renewal, or inspections, without requiring those to whom ready access is requisite to climb over or remove obstacles or to resort to portable ladders, chairs, etc. (See "Accessible.")
    Receptacle. A receptacle is a contact device installed at the outlet for the connection of a single attachment plug. A single receptacle is a single contact device with no other contact device on the same yoke. A multiple receptacle is a single device containing two or more receptacles.
    Receptacle outlet. An outlet where one or more receptacles are installed.
    Remote-control circuit. Any electric circuit that controls any other circuit through a relay or an equivalent device.
    Sealable equipment. Equipment enclosed in a case or cabinet that is provided with a means of sealing or locking so that live parts cannot be made accessible without opening the enclosure. The equipment may or may not be operable without opening the enclosure.
    Separately derived system. A premises wiring system whose power is derived from generator, transformer, or converter windings and has no direct electrical connection, including a solidly connected grounded circuit conductor, to supply conductors originating in another system.
    Service. The conductors and equipment for delivering energy from the electricity supply system to the wiring system of the premises served.
    Service conductors. The supply conductors that extend from the street main or from transformers to the service equipment of the premises supplied.
    Service drop. The overhead service conductors from the last pole or other aerial support to and including the splices, if any, connecting to the service-entrance conductors at the building or other structure.
    Service-entrance conductors, overhead system. The service conductors between the terminals of the service equipment and a point usually outside the building, clear of building walls, where joined by tap or splice to the service drop.
    Service-entrance conductors, underground system. The service conductors between the terminals of the service equipment and the point of connection to the service lateral. Where service equipment is located outside the building walls, there may be no service-entrance conductors, or they may be entirely outside the building.
    Service equipment. The necessary equipment, usually consisting of a circuit breaker or switch and fuses, and their accessories, located near the point of entrance of supply conductors to a building or other structure, or an otherwise defined area, and intended to constitute the main control and means of cutoff of the supply.
    Service raceway. The raceway that encloses the service-entrance conductors.
    Signaling circuit. Any electric circuit that energizes signaling equipment.
    Switchboard. A large single panel, frame, or assembly of panels which have switches, buses, instruments, overcurrent and other protective devices mounted on the face or back or both. Switchboards are generally accessible from the rear as well as from the front and are not intended to be installed in cabinets. (See "Panelboard.")
    Switches -- (a) General-use switch. A switch intended for use in general distribution and branch circuits. It is rated in amperes, and it is capable of interrupting its rated current at its rated voltage.
    (b) General-use snap switch. A form of general-use switch so constructed that it can be installed in flush device boxes or on outlet box covers, or otherwise used in conjunction with wiring systems recognized by this subpart.
    (c) Isolating switch. A switch intended for isolating an electric circuit from the source of power. It has no interrupting rating, and it is intended to be operated only after the circuit has been opened by some other means.
    (d) Motor-circuit switch. A switch, rated in horsepower, capable of interrupting the maximum operating overload current of a motor of the same horsepower rating as the switch at the rated voltage.
    Switching devices. (Over 600 volts, nominal.) Devices designed to close and/or open one or more electric circuits. Included in this category are circuit breakers, cutouts, disconnecting (or isolating) switches, disconnecting means, and interrupter switches.
    Transportable X-ray. X-ray equipment installed in a vehicle or that may readily be disassembled for transport in a vehicle.
    Utilization equipment. Utilization equipment means equipment which utilizes electric energy for mechanical, chemical, heating, lighting, or similar useful purpose.
    Utilization system. A utilization system is a system which provides electric power and light for employee workplaces, and includes the premises wiring system and utilization equipment.
    Ventilated. Provided with a means to permit circulation of air sufficient to remove an excess of heat, fumes, or vapors.
    Volatile flammable liquid. A flammable liquid having a flash point below 38 degrees C (100 degrees F) or whose temperature is above its flash point, or a Class II combustible liquid having a vapor pressure not exceeding 40 psia (276 kPa) at 38 °C (100 °F) whose temperature is above its flash point.
    Voltage. (Of a circuit.) The greatest root-mean-square (effective) difference of potential between any two conductors of the circuit concerned.
    Voltage, nominal. A nominal value assigned to a circuit or system for the purpose of conveniently designating its voltage class (as 120/240, 480Y/277, 600, etc.). The actual voltage at which a circuit operates can vary from the nominal within a range that permits satisfactory operation of equipment.
    Voltage to ground. For grounded circuits, the voltage between the given conductor and that point or conductor of the circuit that is grounded; for ungrounded circuits, the greatest voltage between the given conductor and any other conductor of the circuit.
    Watertight. So constructed that moisture will not enter the enclosure.
    Weatherproof. So constructed or protected that exposure to the weather will not interfere with successful operation. Rainproof, raintight, or watertight equipment can fulfill the requirements for weatherproof where varying weather conditions other than wetness, such as snow, ice, dust, or temperature extremes, are not a factor.
    Wet location. See "Location."
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Electronic Code of Federal Regulations
e-CFR data is current as of May 24, 2021
Title 29: Labor 
PART 1910 -- OCCUPATIONAL SAFETY AND HEALTH STANDARDS 
Subpart S -- Electrical 

Design Safety Standards for Electrical Systems
    Source: Sections 1910.302 through 1910.308 appear at 72 FR 7190, Feb. 14, 2007, unless otherwise noted.
§1910.302   Electric utilization systems.
    Sections 1910.302 through 1910.308 contain design safety standards for electric utilization systems.
    (a) Scope -- (1) Covered. The provisions of §§1910.302 through 1910.308 cover electrical installations and utilization equipment installed or used within or on buildings, structures, and other premises, including:
    (i) Yards;
    (ii) Carnivals;
    (iii) Parking and other lots;
    (iv) Mobile homes;
    (v) Recreational vehicles;
    (vi) Industrial substations;
    (vii) Conductors that connect the installations to a supply of electricity; and
    (viii) Other outside conductors on the premises.
    (2) Not covered. The provisions of §§1910.302 through 1910.308 do not cover:
    (i) Installations in ships, watercraft, railway rolling stock, aircraft, or automotive vehicles other than mobile homes and recreational vehicles;
    (ii) Installations underground in mines;
    (iii) Installations of railways for generation, transformation, transmission, or distribution of power used exclusively for operation of rolling stock or installations used exclusively for signaling and communication purposes;
    (iv) Installations of communication equipment under the exclusive control of communication utilities, located outdoors or in building spaces used exclusively for such installations; or
    (v) Installations under the exclusive control of electric utilities for the purpose of communication or metering; or for the generation, control, transformation, transmission, and distribution of electric energy located in buildings used exclusively by utilities for such purposes or located outdoors on property owned or leased by the utility or on public highways, streets, roads, etc., or outdoors by established rights on private property.
    (b) Extent of application -- (1) Requirements applicable to all installations. The following requirements apply to all electrical installations and utilization equipment, regardless of when they were designed or installed:
  §1910.303(b) -- Examination, installation, and use of equipment 
  §1910.303(c)(3) -- Electrical connections -- Splices 
  §1910.303(d) -- Arcing parts 
  §1910.303(e) -- Marking 
  §1910.303(f), except (f)(4) and (f)(5) -- Disconnecting means and circuits 
  §1910.303(g)(2) -- 600 volts or less -- Guarding of live parts 
  §1910.304(a)(3) -- Use of grounding terminals and devices 
  §1910.304(f)(1)(i), (f)(1)(iv), and (f)(1)(v) -- Overcurrent protection -- 600 volts, nominal, or less 
  §1910.304(g)(1)(ii), (g)(1)(iii), (g)(1)(iv), and (g)(1)(v) -- Grounding -- Systems to be grounded 
  §1910.304(g)(4) -- Grounding -- Grounding connections 
  §1910.304(g)(5) -- Grounding -- Grounding path 
  §1910.304(g)(6)(iv)(A) through (g)(6)(iv)(D), and (g)(6)(vi) -- Grounding -- Supports, enclosures, and equipment to be grounded 
  §1910.304(g)(7) -- Grounding -- Nonelectrical equipment 
  §1910.304(g)(8)(i) -- Grounding -- Methods of grounding fixed equipment 
  §1910.305(g)(1) -- Flexible cords and cables -- Use of flexible cords and cables 
  §1910.305(g)(2)(ii) and (g)(2)(iii) -- Flexible cords and cables -- Identification, splices, and terminations 
  §1910.307, except as specified in §1910.307(b) -- Hazardous (classified) locations
    (2) Requirements applicable to installations made after March 15, 1972. Every electrical installation and all utilization equipment installed or overhauled after March 15, 1972, shall comply with the provisions of §§1910.302 through 1910.308, except as noted in paragraphs (b)(3) and (b)(4) of this section.
    (3) Requirements applicable only to installations made after April 16, 1981. The following requirements apply only to electrical installations and utilization equipment installed after April 16, 1981:
  §1910.303(h)(4) -- Over 600 volts, nominal -- Entrance and access to work space 
  §1910.304(f)(1)(vii) and (f)(1)(viii) -- Overcurrent protection -- 600 volts, nominal, or less 
  §1910.304(g)(9)(i) -- Grounding -- Grounding of systems and circuits of 1000 volts and over (high voltage) 
  §1910.305(j)(6)(ii)(D) -- Equipment for general use -- Capacitors 
  §1910.306(c)(9) -- Elevators, dumbwaiters, escalators, moving walks, wheelchair lifts, and stairway chair lifts -- Interconnection between multicar controllers 
  §1910.306(i) -- Electrically driven or controlled irrigation machines 
  §1910.306(j)(5) -- Swimming pools, fountains, and similar installations -- Fountains 
  §1910.308(a)(1)(ii) -- Systems over 600 volts, nominal -- Aboveground wiring methods 
  §1910.308(c)(2) -- Class 1, Class 2, and Class 3 remote control, signaling, and power-limited circuits -- Marking 
  §1910.308(d) -- Fire alarm systems
    (4) Requirements applicable only to installations made after August 13, 2007. The following requirements apply only to electrical installations and utilization equipment installed after August 13, 2007:
  §1910.303(f)(4) -- Disconnecting means and circuits -- Capable of accepting a lock 
  §1910.303(f)(5) -- Disconnecting means and circuits -- Marking for series combination ratings 
  §1910.303(g)(1)(iv) and (g)(1)(vii) -- 600 Volts, nominal, or less -- Space about electric equipment 
  §1910.303(h)(5)(vi) -- Over 600 volts, nominal -- Working space and guarding 
  §1910.304(b)(1) -- Branch circuits -- Identification of multiwire branch circuits 
  §1910.304(b)(3)(i) -- Branch circuits -- Ground-fault circuit interrupter protection for personnel 
  §1910.304(f)(2)(i)(A), (f)(2)(i)(B) (but not the introductory text to §1910.304(f)(2)(i)), and (f)(2)(iv)(A) -- Overcurrent protection -- Feeders and branch circuits over 600 volts, nominal 
  §1910.305(c)(3)(ii) -- Switches -- Connection of switches 
  §1910.305(c)(5) -- Switches -- Grounding 
  §1910.306(a)(1)(ii) -- Electric signs and outline lighting -- Disconnecting means 
  §1910.306(c)(4) -- Elevators, dumbwaiters, escalators, moving walks, wheelchair lifts, and stairway chair lifts -- Operation 
  §1910.306(c)(5) -- Elevators, dumbwaiters, escalators, moving walks, wheelchair lifts, and stairway chair lifts -- Location 
  §1910.306(c)(6) -- Elevators, dumbwaiters, escalators, moving walks, wheelchair lifts, and stairway chair lifts -- Identification and signs 
  §1910.306(c)(7) -- Elevators, dumbwaiters, escalators, moving walks, wheelchair lifts, and stairway chair lifts -- Single-car and multicar installations 
  §1910.306(j)(1)(iii) -- Swimming pools, fountains, and similar installations -- Receptacles 
  §1910.306(k) -- Carnivals, circuses, fairs, and similar events 
  §1910.308(a)(5)(v) and (a)(5)(vi)(B) -- Systems over 600 volts, nominal -- Interrupting and isolating devices 
  §1910.308(a)(7)(vi) -- Systems over 600 volts, nominal -- Tunnel installations 
  §1910.308(b)(3) -- Emergency power systems -- Signs 
  §1910.308(c)(3) -- Class 1, Class 2, and Class 3 remote control, signaling, and power-limited circuits -- Separation from conductors of other circuits 
  §1910.308(f) -- Solar photovoltaic systems
    (c) Applicability of requirements for disconnecting means. The requirement in §1910.147(c)(2)(iii) that energy isolating devices be capable of accepting a lockout device whenever replacement or major repair, renovation or modification of a machine or equipment is performed, and whenever new machines or equipment are installed after January 2, 1990, applies in addition to any requirements in §§1910.303 through 1910.308 that disconnecting means be capable of being locked in the open position under certain conditions.
§1910.303   General.
    (a) Approval. The conductors and equipment required or permitted by this subpart shall be acceptable only if approved, as defined in §1910.399.
    (b) Examination, installation, and use of equipment -- (1) Examination. Electric equipment shall be free from recognized hazards that are likely to cause death or serious physical harm to employees. Safety of equipment shall be determined using the following considerations:
    (i) Suitability for installation and use in conformity with the provisions of this subpart;
    Note to paragraph (b)(1)(i) of this section: Suitability of equipment for an identified purpose may be evidenced by listing or labeling for that identified purpose.
    (ii) Mechanical strength and durability, including, for parts designed to enclose and protect other equipment, the adequacy of the protection thus provided;
    (iii) Wire-bending and connection space;
    (iv) Electrical insulation;
    (v) Heating effects under all conditions of use;
    (vi) Arcing effects;
    (vii) Classification by type, size, voltage, current capacity, and specific use; and
    (viii) Other factors that contribute to the practical safeguarding of persons using or likely to come in contact with the equipment.
    (2) Installation and use. Listed or labeled equipment shall be installed and used in accordance with any instructions included in the listing or labeling.
    (3) Insulation integrity. Completed wiring installations shall be free from short circuits and from grounds other than those required or permitted by this subpart.
    (4) Interrupting rating. Equipment intended to interrupt current at fault levels shall have an interrupting rating sufficient for the nominal circuit voltage and the current that is available at the line terminals of the equipment. Equipment intended to interrupt current at other than fault levels shall have an interrupting rating at nominal circuit voltage sufficient for the current that must be interrupted.
    (5) Circuit impedance and other characteristics. The overcurrent protective devices, the total impedance, the component short-circuit current ratings, and other characteristics of the circuit to be protected shall be selected and coordinated to permit the circuit protective devices used to clear a fault to do so without the occurrence of extensive damage to the electrical components of the circuit. This fault shall be assumed to be either between two or more of the circuit conductors, or between any circuit conductor and the grounding conductor or enclosing metal raceway.
    (6) Deteriorating agents. Unless identified for use in the operating environment, no conductors or equipment shall be located in damp or wet locations; where exposed to gases, fumes, vapors, liquids, or other agents that have a deteriorating effect on the conductors or equipment; or where exposed to excessive temperatures.
    (7) Mechanical execution of work. Electric equipment shall be installed in a neat and workmanlike manner.
    (i) Unused openings in boxes, raceways, auxiliary gutters, cabinets, equipment cases, or housings shall be effectively closed to afford protection substantially equivalent to the wall of the equipment.
    (ii) Conductors shall be racked to provide ready and safe access in underground and subsurface enclosures that persons enter for installation and maintenance.
    (iii) Internal parts of electrical equipment, including busbars, wiring terminals, insulators, and other surfaces, may not be damaged or contaminated by foreign materials such as paint, plaster, cleaners, abrasives, or corrosive residues.
    (iv) There shall be no damaged parts that may adversely affect safe operation or mechanical strength of the equipment, such as parts that are broken, bent, cut, or deteriorated by corrosion, chemical action, or overheating.
    (8) Mounting and cooling of equipment. (i) Electric equipment shall be firmly secured to the surface on which it is mounted.
    Note to paragraph (b)(8)(i) of this section: Wooden plugs driven into holes in masonry, concrete, plaster, or similar materials are not considered secure means of fastening electric equipment.
    (ii) Electric equipment that depends on the natural circulation of air and convection principles for cooling of exposed surfaces shall be installed so that room airflow over such surfaces is not prevented by walls or by adjacent installed equipment. For equipment designed for floor mounting, clearance between top surfaces and adjacent surfaces shall be provided to dissipate rising warm air.
    (iii) Electric equipment provided with ventilating openings shall be installed so that walls or other obstructions do not prevent the free circulation of air through the equipment.
    (c) Electrical connections -- (1) General. Because of different characteristics of dissimilar metals:
    (i) Devices such as pressure terminal or pressure splicing connectors and soldering lugs shall be identified for the material of the conductor and shall be properly installed and used;
    (ii) Conductors of dissimilar metals may not be intermixed in a terminal or splicing connector where physical contact occurs between dissimilar conductors (such as copper and aluminum, copper and copper-clad aluminum, or aluminum and copper-clad aluminum) unless the device is identified for the purpose and conditions of use; and
    (iii) Materials such as solder, fluxes, inhibitors, and compounds, where employed, shall be suitable for the use and shall be of a type that will not adversely affect the conductors, installation, or equipment.
    (2) Terminals. (i) Connection of conductors to terminal parts shall ensure a good connection without damaging the conductors and shall be made by means of pressure connectors (including set-screw type), solder lugs, or splices to flexible leads. However, No. 10 or smaller conductors may be connected by means of wire binding screws or studs and nuts having upturned lugs or equivalent.
    (ii) Terminals for more than one conductor and terminals used to connect aluminum shall be so identified.
    (3) Splices. (i) Conductors shall be spliced or joined with splicing devices identified for the use or by brazing, welding, or soldering with a fusible metal or alloy. Soldered splices shall first be spliced or joined to be mechanically and electrically secure without solder and then soldered. All splices and joints and the free ends of conductors shall be covered with an insulation equivalent to that of the conductors or with an insulating device identified for the purpose.
    (ii) Wire connectors or splicing means installed on conductors for direct burial shall be listed for such use.
    (d) Arcing parts. Parts of electric equipment that in ordinary operation produce arcs, sparks, flames, or molten metal shall be enclosed or separated and isolated from all combustible material.
    (e) Marking -- (1) Identification of manufacturer and ratings. Electric equipment may not be used unless the following markings have been placed on the equipment:
    (i) The manufacturer's name, trademark, or other descriptive marking by which the organization responsible for the product may be identified; and
    (ii) Other markings giving voltage, current, wattage, or other ratings as necessary.
    (2) Durability. The marking shall be of sufficient durability to withstand the environment involved.
    (f) Disconnecting means and circuits -- (1) Motors and appliances. Each disconnecting means required by this subpart for motors and appliances shall be legibly marked to indicate its purpose, unless located and arranged so the purpose is evident.
    (2) Services, feeders, and branch circuits. Each service, feeder, and branch circuit, at its disconnecting means or overcurrent device, shall be legibly marked to indicate its purpose, unless located and arranged so the purpose is evident.
    (3) Durability of markings. The markings required by paragraphs (f)(1) and (f)(2) of this section shall be of sufficient durability to withstand the environment involved.
    (4) Capable of accepting a lock. Disconnecting means required by this subpart shall be capable of being locked in the open position.
    (5) Marking for series combination ratings. (i) Where circuit breakers or fuses are applied in compliance with the series combination ratings marked on the equipment by the manufacturer, the equipment enclosures shall be legibly marked in the field to indicate that the equipment has been applied with a series combination rating.
    (ii) The marking required by paragraph (f)(5)(i) of this section shall be readily visible and shall state "Caution -- Series Combination System Rated __ Amperes. Identified Replacement Component Required."
    (g) 600 Volts, nominal, or less. This paragraph applies to electric equipment operating at 600 volts, nominal, or less to ground.
    (1) Space about electric equipment. Sufficient access and working space shall be provided and maintained about all electric equipment to permit ready and safe operation and maintenance of such equipment.
    (i) Working space for equipment likely to require examination, adjustment, servicing, or maintenance while energized shall comply with the following dimensions, except as required or permitted elsewhere in this subpart:
    (A) The depth of the working space in the direction of access to live parts may not be less than indicated in Table S-1. Distances shall be measured from the live parts if they are exposed or from the enclosure front or opening if they are enclosed;
    (B) The width of working space in front of the electric equipment shall be the width of the equipment or 762 mm (30 in.), whichever is greater. In all cases, the working space shall permit at least a 90-degree opening of equipment doors or hinged panels; and
    (C) The work space shall be clear and extend from the grade, floor, or platform to the height required by paragraph (g)(1)(vi) of this section. However, other equipment associated with the electrical installation and located above or below the electric equipment may extend not more than 153 mm (6 in.) beyond the front of the electric equipment.
    (ii) Working space required by this standard may not be used for storage. When normally enclosed live parts are exposed for inspection or servicing, the working space, if in a passageway or general open space, shall be suitably guarded.
    (iii) At least one entrance of sufficient area shall be provided to give access to the working space about electric equipment.
    (iv) For equipment rated 1200 amperes or more and over 1.83 m (6.0 ft) wide, containing overcurrent devices, switching devices, or control devices, there shall be one entrance not less than 610 mm (24 in.) wide and 1.98 m (6.5 ft) high at each end of the working space, except that:
    (A) Where the location permits a continuous and unobstructed way of exit travel, one means of exit is permitted; or
    (B) Where the working space required by paragraph (g)(1)(i) of this section is doubled, only one entrance to the working space is required; however, the entrance shall be located so that the edge of the entrance nearest the equipment is the minimum clear distance given in Table S-1 away from such equipment.
    (v) Illumination shall be provided for all working spaces about service equipment, switchboards, panelboards, and motor control centers installed indoors. Additional lighting fixtures are not required where the working space is illuminated by an adjacent light source. In electric equipment rooms, the illumination may not be controlled by automatic means only.
    (vi) The minimum headroom of working spaces about service equipment, switchboards, panelboards, or motor control centers shall be as follows:
    (A) For installations built before August 13, 2007, 1.91 m (6.25 ft); and
    (B) For installations built on or after August 13, 2007, 1.98 m (6.5 ft), except that where the electrical equipment exceeds 1.98 m (6.5 ft) in height, the minimum headroom may not be less than the height of the equipment.
    Table S-1 -- Minimum Depth of Clear Working Space at Electric Equipment, 600 V or Less 
Nominal voltage to ground 
Minimum clear distance for condition[23] 

Condition A 
Condition B 
Condition C 

m 
ft 
m 
ft 
m 
ft 
0-150
[1]0.9
[1]3.0
[1]0.9
[1]3.0
0.9
3.0 
151-600
[1]0.9
[1]3.0
1.0
3.5
1.2
4.0 
    Notes to Table S-1: 
      1. Minimum clear distances may be 0.7 m (2.5 ft) for installations built before April 16, 1981.
      2. Conditions A, B, and C are as follows:
       Condition A -- Exposed live parts on one side and no live or grounded parts on the other side of the working space, or exposed live parts on both sides effectively guarded by suitable wood or other insulating material. Insulated wire or insulated busbars operating at not over 300 volts are not considered live parts.
       Condition B -- Exposed live parts on one side and grounded parts on the other side.
       Condition C -- Exposed live parts on both sides of the work space (not guarded as provided in Condition A) with the operator between.
      3. Working space is not required in back of assemblies such as dead-front switchboards or motor control centers where there are no renewable or adjustable parts (such as fuses or switches) on the back and where all connections are accessible from locations other than the back. Where rear access is required to work on deenergized parts on the back of enclosed equipment, a minimum working space of 762 mm (30 in.) horizontally shall be provided.
    (vii) Switchboards, panelboards, and distribution boards installed for the control of light and power circuits, and motor control centers shall be located in dedicated spaces and protected from damage.
    (A) For indoor installation, the dedicated space shall comply with the following:
    (1) The space equal to the width and depth of the equipment and extending from the floor to a height of 1.83 m (6.0 ft) above the equipment or to the structural ceiling, whichever is lower, shall be dedicated to the electrical installation. Unless isolated from equipment by height or physical enclosures or covers that will afford adequate mechanical protection from vehicular traffic or accidental contact by unauthorized personnel or that complies with paragraph (g)(1)(vii)(A)(2) of this section, piping, ducts, or equipment foreign to the electrical installation may not be located in this area;
    (2) The space equal to the width and depth of the equipment shall be kept clear of foreign systems unless protection is provided to avoid damage from condensation, leaks, or breaks in such foreign systems. This area shall extend from the top of the electric equipment to the structural ceiling;
    (3) Sprinkler protection is permitted for the dedicated space where the piping complies with this section; and
    (4) Control equipment that by its very nature or because of other requirements in this subpart must be adjacent to or within sight of its operating machinery is permitted in the dedicated space.
    Note to paragraph (g)(1)(vii)(A) of this section: A dropped, suspended, or similar ceiling that does not add strength to the building structure is not considered a structural ceiling.
    (B) Outdoor electric equipment shall be installed in suitable enclosures and shall be protected from accidental contact by unauthorized personnel, or by vehicular traffic, or by accidental spillage or leakage from piping systems. No architectural appurtenance or other equipment may be located in the working space required by paragraph (g)(1)(i) of this section.
    (2) Guarding of live parts. (i) Except as elsewhere required or permitted by this standard, live parts of electric equipment operating at 50 volts or more shall be guarded against accidental contact by use of approved cabinets or other forms of approved enclosures or by any of the following means:
    (A) By location in a room, vault, or similar enclosure that is accessible only to qualified persons;
    (B) By suitable permanent, substantial partitions or screens so arranged so that only qualified persons will have access to the space within reach of the live parts. Any openings in such partitions or screens shall be so sized and located that persons are not likely to come into accidental contact with the live parts or to bring conducting objects into contact with them;
    (C) By placement on a suitable balcony, gallery, or platform so elevated and otherwise located as to prevent access by unqualified persons; or
    (D) By elevation of 2.44 m (8.0 ft) or more above the floor or other working surface.
    (ii) In locations where electric equipment is likely to be exposed to physical damage, enclosures or guards shall be so arranged and of such strength as to prevent such damage.
    (iii) Entrances to rooms and other guarded locations containing exposed live parts shall be marked with conspicuous warning signs forbidding unqualified persons to enter.
    (h) Over 600 volts, nominal -- (1) General. Conductors and equipment used on circuits exceeding 600 volts, nominal, shall comply with all applicable provisions of the paragraphs (a) through (g) of this section and with the following provisions, which supplement or modify the preceding requirements. However, paragraphs (h)(2), (h)(3), and (h)(4) of this section do not apply to the equipment on the supply side of the service point.
    (2) Enclosure for electrical installations. (i) Electrical installations in a vault, room, or closet or in an area surrounded by a wall, screen, or fence, access to which is controlled by lock and key or other approved means, are considered to be accessible to qualified persons only. The type of enclosure used in a given case shall be designed and constructed according to the hazards associated with the installation.
    (ii) For installations other than equipment described in paragraph (h)(2)(v) of this section, a wall, screen, or fence shall be used to enclose an outdoor electrical installation to deter access by persons who are not qualified. A fence may not be less than 2.13 m (7.0 ft) in height or a combination of 1.80 m (6.0 ft) or more of fence fabric and a 305-mm (1-ft) or more extension utilizing three or more strands of barbed wire or equivalent.
    (iii) The following requirements apply to indoor installations that are accessible to other than qualified persons:
    (A) The installations shall be made with metal-enclosed equipment or shall be enclosed in a vault or in an area to which access is controlled by a lock;
    (B) Metal-enclosed switchgear, unit substations, transformers, pull boxes, connection boxes, and other similar associated equipment shall be marked with appropriate caution signs; and
    (C) Openings in ventilated dry-type transformers and similar openings in other equipment shall be designed so that foreign objects inserted through these openings will be deflected from energized parts.
    (iv) Outdoor electrical installations having exposed live parts shall be accessible to qualified persons only.
    (v) The following requirements apply to outdoor enclosed equipment accessible to unqualified employees:
    (A) Ventilating or similar openings in equipment shall be so designed that foreign objects inserted through these openings will be deflected from energized parts;
    (B) Where exposed to physical damage from vehicular traffic, suitable guards shall be provided;
    (C) Nonmetallic or metal-enclosed equipment located outdoors and accessible to the general public shall be designed so that exposed nuts or bolts cannot be readily removed, permitting access to live parts;
    (D) Where nonmetallic or metal-enclosed equipment is accessible to the general public and the bottom of the enclosure is less than 2.44 m (8.0 ft) above the floor or grade level, the enclosure door or hinged cover shall be kept locked; and
    (E) Except for underground box covers that weigh over 45.4 kg (100 lb), doors and covers of enclosures used solely as pull boxes, splice boxes, or junction boxes shall be locked, bolted, or screwed on.
    (3) Work space about equipment. Sufficient space shall be provided and maintained about electric equipment to permit ready and safe operation and maintenance of such equipment. Where energized parts are exposed, the minimum clear work space may not be less than 1.98 m (6.5 ft) high (measured vertically from the floor or platform) or less than 914 mm (3.0 ft) wide (measured parallel to the equipment). The depth shall be as required in paragraph (h)(5)(i) of this section. In all cases, the work space shall be adequate to permit at least a 90-degree opening of doors or hinged panels.
    (4) Entrance and access to work space. (i) At least one entrance not less than 610 mm (24 in.) wide and 1.98 m (6.5 ft) high shall be provided to give access to the working space about electric equipment.
    (A) On switchboard and control panels exceeding 1.83 m (6.0 ft) in width, there shall be one entrance at each end of such boards unless the location of the switchboards and control panels permits a continuous and unobstructed way of exit travel, or unless the work space required in paragraph (h)(5)(i) of this section is doubled.
    (B) Where one entrance to the working space is permitted under the conditions described in paragraph (h)(4)(i)(A) of this section, the entrance shall be located so that the edge of the entrance nearest the switchboards and control panels is at least the minimum clear distance given in Table S-2 away from such equipment.
    (C) Where bare energized parts at any voltage or insulated energized parts above 600 volts, nominal, to ground are located adjacent to such entrance, they shall be suitably guarded.
    (ii) Permanent ladders or stairways shall be provided to give safe access to the working space around electric equipment installed on platforms, balconies, mezzanine floors, or in attic or roof rooms or spaces.
    (5) Working space and guarding. (i) Except as elsewhere required or permitted in this subpart, the minimum clear working space in the direction of access to live parts of electric equipment may not be less than specified in Table S-2. Distances shall be measured from the live parts, if they are exposed, or from the enclosure front or opening, if they are enclosed.
    (ii) If switches, cutouts, or other equipment operating at 600 volts, nominal, or less, are installed in a room or enclosure where there are exposed live parts or exposed wiring operating at over 600 volts, nominal, the high-voltage equipment shall be effectively separated from the space occupied by the low-voltage equipment by a suitable partition, fence, or screen. However, switches or other equipment operating at 600 volts, nominal, or less, and serving only equipment within the high-voltage vault, room, or enclosure may be installed in the high-voltage enclosure, room, or vault if accessible to qualified persons only.
    (iii) The following requirements apply to the entrances to all buildings, rooms, or enclosures containing exposed live parts or exposed conductors operating at over 600 volts, nominal:
    (A) The entrances shall be kept locked unless they are under the observation of a qualified person at all times; and
    (B) Permanent and conspicuous warning signs shall be provided, reading substantially as follows:
"DANGER -- HIGH VOLTAGE -- KEEP OUT."
    (iv) Illumination shall be provided for all working spaces about electric equipment.
    (A) The lighting outlets shall be arranged so that persons changing lamps or making repairs on the lighting system will not be endangered by live parts or other equipment.
    (B) The points of control shall be located so that persons are prevented from contacting any live part or moving part of the equipment while turning on the lights.
    (v) Unguarded live parts above working space shall be maintained at elevations not less than specified in Table S-3.
    (vi) Pipes or ducts that are foreign to the electrical installation and that require periodic maintenance or whose malfunction would endanger the operation of the electrical system may not be located in the vicinity of service equipment, metal-enclosed power switchgear, or industrial control assemblies. Protection shall be provided where necessary to avoid damage from condensation leaks and breaks in such foreign systems.
    Note to paragraph (h)(5)(vi) of this section: Piping and other facilities are not considered foreign if provided for fire protection of the electrical installation.
    Table S-2 -- Minimum Depth of Clear Working Space at Electric Equipment, Over 600 V 
Nominal voltage to ground 
Minimum clear distance for condition[23] 

Condition A 
Condition B 
Condition C 

m 
ft 
m 
ft 
m 
ft 
601-2500 V
0.9
3.0
1.2
4.0
1.5
5.0 
2501-9000 V
1.2
4.0
1.5
5.0
1.8
6.0 
9001 V-25 kV
1.5
5.0
1.8
6.0
2.8
9.0 
Over 25-75 kV[1]
1.8
6.0
2.5
8.0
3.0
10.0 
Above 75 kV[1]
2.5
8.0
3.0
10.0
3.7
12.0 
    Notes to Table S-2:
    1Minimum depth of clear working space in front of electric equipment with a nominal voltage to ground above 25,000 volts may be the same as that for 25,000 volts under Conditions A, B, and C for installations built before April 16, 1981.
    2Conditions A, B, and C are as follows:
    Condition A -- Exposed live parts on one side and no live or grounded parts on the other side of the working space, or exposed live parts on both sides effectively guarded by suitable wood or other insulating material. Insulated wire or insulated busbars operating at not over 300 volts are not considered live parts.
    Condition B -- Exposed live parts on one side and grounded parts on the other side. Concrete, brick, and tile walls are considered as grounded surfaces.
    Condition C -- Exposed live parts on both sides of the work space (not guarded as provided in Condition A) with the operator between.
    3Working space is not required in back of equipment such as dead-front switchboards or control assemblies that has no renewable or adjustable parts (such as fuses or switches) on the back and where all connections are accessible from locations other than the back. Where rear access is required to work on the deenergized parts on the back of enclosed equipment, a minimum working space 762 mm (30 in.) horizontally shall be provided.
    Table S-3 -- Elevation of Unguarded Live Parts Above Working Space 
Nominal voltage between phases 
Elevation 

m 
ft 
601-7500 V
[1]2.8
[1]9.0.
7501 V-35 kV
2.8
9.0.
Over 35 kV
2.8 + 9.5 mm/kV over 35 kV
9.0 + 0.37 in./kV over 35 kV.
    1The minimum elevation may be 2.6 m (8.5 ft) for installations built before August 13, 2007. The minimum elevation may be 2.4 m (8.0 ft) for installations built before April 16, 1981, if the nominal voltage between phases is in the range of 601-6600 volts.
[46 FR 4056, Jan. 16, 1981, as amended at 73 FR 64205, Oct. 29, 2008]
§1910.304   Wiring design and protection.
    (a) Use and identification of grounded and grounding conductors -- (1) Identification of conductors. (i) A conductor used as a grounded conductor shall be identifiable and distinguishable from all other conductors.
    (ii) A conductor used as an equipment grounding conductor shall be identifiable and distinguishable from all other conductors.
    (2) Polarity of connections. No grounded conductor may be attached to any terminal or lead so as to reverse designated polarity.
    (3) Use of grounding terminals and devices. A grounding terminal or grounding-type device on a receptacle, cord connector, or attachment plug may not be used for purposes other than grounding.
    (b) Branch circuits -- (1) Identification of multiwire branch circuits. Where more than one nominal voltage system exists in a building containing multiwire branch circuits, each ungrounded conductor of a multiwire branch circuit, where accessible, shall be identified by phase and system. The means of identification shall be permanently posted at each branch-circuit panelboard.
    (2) Receptacles and cord connectors. (i) Receptacles installed on 15- and 20-ampere branch circuits shall be of the grounding type except as permitted for replacement receptacles in paragraph (b)(2)(iv) of this section. Grounding-type receptacles shall be installed only on circuits of the voltage class and current for which they are rated, except as provided in Table S-4 and Table S-5.
    (ii) Receptacles and cord connectors having grounding contacts shall have those contacts effectively grounded except for receptacles mounted on portable and vehicle-mounted generators in accordance with paragraph (g)(3) of this section and replacement receptacles installed in accordance with paragraph (b)(2)(iv) of this section.
    (iii) The grounding contacts of receptacles and cord connectors shall be grounded by connection to the equipment grounding conductor of the circuit supplying the receptacle or cord connector. The branch circuit wiring method shall include or provide an equipment grounding conductor to which the grounding contacts of the receptacle or cord connector shall be connected.
    (iv) Replacement of receptacles shall comply with the following requirements:
    (A) Where a grounding means exists in the receptacle enclosure or a grounding conductor is installed, grounding-type receptacles shall be used and shall be connected to the grounding means or conductor;
    (B) Ground-fault circuit-interrupter protected receptacles shall be provided where replacements are made at receptacle outlets that are required to be so protected elsewhere in this subpart; and
    (C) Where a grounding means does not exist in the receptacle enclosure, the installation shall comply with one of the following provisions:
    (1) A nongrounding-type receptacle may be replaced with another nongrounding-type receptacle; or
    (2) A nongrounding-type receptacle may be replaced with a ground-fault circuit-interrupter-type of receptacle that is marked "No Equipment Ground;" an equipment grounding conductor may not be connected from the ground-fault circuit-interrupter-type receptacle to any outlet supplied from the ground-fault circuit-interrupter receptacle; or
    (3) A nongrounding-type receptacle may be replaced with a grounding-type receptacle where supplied through a ground-fault circuit-interrupter; the replacement receptacle shall be marked "GFCI Protected" and "No Equipment Ground;" an equipment grounding conductor may not be connected to such grounding-type receptacles.
    (v) Receptacles connected to circuits having different voltages, frequencies, or types of current (ac or dc) on the same premises shall be of such design that the attachment plugs used on these circuits are not interchangeable.
    (3) Ground-fault circuit interrupter protection for personnel. (i) All 125-volt, single-phase, 15- and 20-ampere receptacles installed in bathrooms or on rooftops shall have ground-fault circuit-interrupter protection for personnel.
    (ii) The following requirements apply to temporary wiring installations that are used during construction-like activities, including certain maintenance, remodeling, or repair activities, involving buildings, structures or equipment.
    (A) All 125-volt, single-phase,15-, 20-, and 30-ampere receptacle outlets that are not part of the permanent wiring of the building or structure and that are in use by personnel shall have ground-fault circuit-interrupter protection for personnel.
    Note 1 to paragraph (b)(3)(ii)(A) of this section: A cord connector on an extension cord set is considered to be a receptacle outlet if the cord set is used for temporary electric power.
    Note 2 to paragraph (b)(3)(ii)(A) of this section: Cord sets and devices incorporating the required ground-fault circuit-interrupter that are connected to the receptacle closest to the source of power are acceptable forms of protection.
    (B) Receptacles other than 125 volt, single-phase, 15-, 20-, and 30-ampere receptacles that are not part of the permanent wiring of the building or structure and that are in use by personnel shall have ground-fault circuit-interrupter protection for personnel.
    (C) Where the ground-fault circuit-interrupter protection required by paragraph (b)(3)(ii)(B) of this section is not available for receptacles other than 125-volt, single-phase, 15-, 20-, and 30-ampere, the employer shall establish and implement an assured equipment grounding conductor program covering cord sets, receptacles that are not a part of the building or structure, and equipment connected by cord and plug that are available for use or used by employees on those receptacles. This program shall comply with the following requirements:
    (1) A written description of the program, including the specific procedures adopted by the employer, shall be available at the jobsite for inspection and copying by the Assistant Secretary of Labor and any affected employee;
    (2) The employer shall designate one or more competent persons to implement the program;
    (3) Each cord set, attachment cap, plug, and receptacle of cord sets, and any equipment connected by cord and plug, except cord sets and receptacles which are fixed and not exposed to damage, shall be visually inspected before each day's use for external defects, such as deformed or missing pins or insulation damage, and for indications of possible internal damage. Equipment found damaged or defective shall not be used until repaired;
    (4) The following tests shall be performed on all cord sets and receptacles which are not a part of the permanent wiring of the building or structure, and cord- and plug-connected equipment required to be grounded:
    (i) All equipment grounding conductors shall be tested for continuity and shall be electrically continuous;
    (ii) Each receptacle and attachment cap or plug shall be tested for correct attachment of the equipment grounding conductor. The equipment grounding conductor shall be connected to its proper terminal; and
    (iii) All required tests shall be performed before first use; before equipment is returned to service following any repairs; before equipment is used after any incident which can be reasonably suspected to have caused damage (for example, when a cord set is run over); and at intervals not to exceed 3 months, except that cord sets and receptacles which are fixed and not exposed to damage shall be tested at intervals not exceeding 6 months;
    (5) The employer shall not make available or permit the use by employees of any equipment which has not met the requirements of paragraph (b)(3)(ii)(C) of this section; and
    (6) Tests performed as required in paragraph (b)(3)(ii)(C) of this section shall be recorded. This test record shall identify each receptacle, cord set, and cord- and plug-connected equipment that passed the test and shall indicate the last date it was tested or the interval for which it was tested. This record shall be kept by means of logs, color coding, or other effective means and shall be maintained until replaced by a more current record. The record shall be made available on the jobsite for inspection by the Assistant Secretary and any affected employee.
    (4) Outlet devices. Outlet devices shall have an ampere rating not less than the load to be served and shall comply with the following provisions:
    (i) Where connected to a branch circuit having a rating in excess of 20 amperes, lampholders shall be of the heavy-duty type. A heavy-duty lampholder shall have a rating of not less than 660 watts if of the admedium type and not less than 750 watts if of any other type; and
    (ii) Receptacle outlets shall comply with the following provisions:
    (A) A single receptacle installed on an individual branch circuit shall have an ampere rating of not less than that of the branch circuit;
    (B) Where connected to a branch circuit supplying two or more receptacles or outlets, a receptacle may not supply a total cord- and plug-connected load in excess of the maximum specified in Table S-4; and
    (C) Where connected to a branch circuit supplying two or more receptacles or outlets, receptacle ratings shall conform to the values listed in Table S-5; or, where larger than 50 amperes, the receptacle rating may not be less than the branch-circuit rating. However, receptacles of cord- and plug-connected arc welders may have ampere ratings not less than the minimum branch-circuit conductor ampacity.
    (5) Cord connections. A receptacle outlet shall be installed wherever flexible cords with attachment plugs are used. Where flexible cords are permitted to be permanently connected, receptacles may be omitted.
    Table S-4 -- Maximum Cord- and Plug-Connected Load to Receptacle 
Circuit rating
(amperes) 
Receptacle
rating
(amperes) 
Maximum
load
(amperes) 
15 or 20
15
12 
20
20
16 
30
30
24
    Table S-5 -- Receptacle Ratings for Various Size Circuits 
Circuit rating
(amperes) 
Receptacle rating
(amperes) 
15
Not over 15.
20
15 or 20.
30
30.
40
40 or 50.
50
50.
    (c) Outside conductors, 600 volts, nominal, or less. The following requirements apply to branch-circuit, feeder, and service conductors rated 600 volts, nominal, or less and run outdoors as open conductors.
    (1) Conductors on poles. Conductors on poles shall have a separation of not less than 305 mm (1.0 ft) where not placed on racks or brackets. Conductors supported on poles shall provide a horizontal climbing space not less than the following:
    (i) Power conductors below communication conductors -- 762 mm (30 in.);
    (ii) Power conductors alone or above communication conductors:
    (A) 300 volts or less -- 610 mm (24 in.),
    (B) Over 300 volts -- 762 mm (30 in.);
    (iii) Communication conductors below power conductors -- same as power conductors; and
    (iv) Communications conductors alone -- no requirement.
    (2) Clearance from ground. Open conductors, open multiconductor cables, and service-drop conductors of not over 600 volts, nominal, shall conform to the minimum clearances specified in Table S-6.
    Table S-6 -- Clearances From Ground
Distance
Installations built before August 13, 2007
Installations built on or after August 13, 2007

Maximum voltage
Conditions
Voltage
to
ground
Conditions
3.05 m (10.0 ft)
<600 V
Above finished grade or sidewalks, or from any platform or projection from which they might be reached. (If these areas are accessible to other than pedestrian traffic, then one of the other conditions applies)
<150 V
Above finished grade or sidewalks, or from any platform or projection from which they might be reached. (If these areas are accessible to other than pedestrian traffic, then one of the other conditions applies.)
3.66 m (12.0 ft)
<600 V
Over areas, other than public streets, alleys, roads, and driveways, subject to vehicular traffic other than truck traffic
<300 V
Over residential property and driveways. Over commercial areas subject to pedestrian traffic or to vehicular traffic other than truck traffic. (This category includes conditions covered under the 3.05-m (10.0-ft) category where the voltage exceeds 150 V.)
4.57 m (15.0 ft)
<600 V
Over areas, other than public streets, alleys, roads, and driveways, subject to truck traffic
301 to 600 V
Over residential property and driveways. Over commercial areas subject to pedestrian traffic or to vehicular traffic other than truck traffic. (This category includes conditions covered under the 3.05-m (10.0-ft) category where the voltage exceeds 300 V.)
5.49 m (18.0 ft)
<600 V
Over public streets, alleys, roads, and driveways
<600 V
Over public streets, alleys, roads, and driveways. Over commercial areas subject to truck traffic. Other land traversed by vehicles, including land used for cultivating or grazing and forests and orchards.
    (3) Clearance from building openings. (i) Service conductors installed as open conductors or multiconductor cable without an overall outer jacket shall have a clearance of not less than 914 mm (3.0 ft) from windows that are designed to be opened, doors, porches, balconies, ladders, stairs, fire escapes, and similar locations. However, conductors that run above the top level of a window may be less than 914 mm (3.0 ft) from the window. Vertical clearance of final spans above, or within 914 mm (3.0 ft) measured horizontally of, platforms, projections, or surfaces from which they might be reached shall be maintained in accordance with paragraph (c)(2) of this section.
    (ii) Overhead service conductors may not be installed beneath openings through which materials may be moved, such as openings in farm and commercial buildings, and may not be installed where they will obstruct entrance to these building openings.
    (4) Above roofs. Overhead spans of open conductors and open multiconductor cables shall have a vertical clearance of not less than 2.44 m (8.0 ft) above the roof surface. The vertical clearance above the roof level shall be maintained for a distance not less than 914 mm (3.0 ft) in all directions from the edge of the roof.
    (i) The area above a roof surface subject to pedestrian or vehicular traffic shall have a vertical clearance from the roof surface in accordance with the clearance requirements of paragraph (c)(2) of this section.
    (ii) A reduction in clearance to 914 mm (3.0 ft) is permitted where the voltage between conductors does not exceed 300 and the roof has a slope of 102 mm (4 in.) in 305 mm (12 in.) or greater.
    (iii) A reduction in clearance above only the overhanging portion of the roof to not less than 457 mm (18 in.) is permitted where the voltage between conductors does not exceed 300 if:
    (A) The conductors do not pass above the roof overhang for a distance of more than 1.83 m (6.0 ft), 1.22 m (4.0 ft) horizontally, and
    (B) The conductors are terminated at a through-the-roof raceway or approved support.
    (iv) The requirement for maintaining a vertical clearance of 914 mm (3.0 ft) from the edge of the roof does not apply to the final conductor span, where the conductors are attached to the side of a building.
    (d) Location of outdoor lamps. Lamps for outdoor lighting shall be located below all energized conductors, transformers, or other electric equipment, unless such equipment is controlled by a disconnecting means that can be locked in the open position, or unless adequate clearances or other safeguards are provided for relamping operations.
    (e) Services -- (1) Disconnecting means. (i) Means shall be provided to disconnect all conductors in a building or other structure from the service-entrance conductors. The service disconnecting means shall plainly indicate whether it is in the open or closed position and shall be installed at a readily accessible location nearest the point of entrance of the service-entrance conductors.
    (ii) Each service disconnecting means shall simultaneously disconnect all ungrounded conductors.
    (iii) Each service disconnecting means shall be suitable for the prevailing conditions.
    (2) Services over 600 volts, nominal. The following additional requirements apply to services over 600 volts, nominal.
    (i) Service-entrance conductors installed as open wires shall be guarded to make them accessible only to qualified persons.
    (ii) Signs warning of high voltage shall be posted where unqualified employees might come in contact with live parts.
    (f) Overcurrent protection -- (1) 600 volts, nominal, or less. The following requirements apply to overcurrent protection of circuits rated 600 volts, nominal, or less.
    (i) Conductors and equipment shall be protected from overcurrent in accordance with their ability to safely conduct current.
    (ii) Except for motor running overload protection, overcurrent devices may not interrupt the continuity of the grounded conductor unless all conductors of the circuit are opened simultaneously.
    (iii) A disconnecting means shall be provided on the supply side of all fuses in circuits over 150 volts to ground and cartridge fuses in circuits of any voltage where accessible to other than qualified persons so that each individual circuit containing fuses can be independently disconnected from the source of power. However, a current-limiting device without a disconnecting means is permitted on the supply side of the service disconnecting means. In addition, a single disconnecting means is permitted on the supply side of more than one set of fuses as permitted by the exception in §1910.305(j)(4)(vi) for group operation of motors, and a single disconnecting means is permitted for fixed electric space-heating equipment.
    (iv) Overcurrent devices shall be readily accessible to each employee or authorized building management personnel. These overcurrent devices may not be located where they will be exposed to physical damage or in the vicinity of easily ignitable material.
    (v) Fuses and circuit breakers shall be so located or shielded that employees will not be burned or otherwise injured by their operation. Handles or levers of circuit breakers, and similar parts that may move suddenly in such a way that persons in the vicinity are likely to be injured by being struck by them, shall be guarded or isolated.
    (vi) Circuit breakers shall clearly indicate whether they are in the open (off) or closed (on) position.
    (vii) Where circuit breaker handles on switchboards are operated vertically rather than horizontally or rotationally, the up position of the handle shall be the closed (on) position.
    (viii) Circuit breakers used as switches in 120-volt and 277-volt, fluorescent lighting circuits shall be listed and marked "SWD."
    (ix) A circuit breaker with a straight voltage rating, such as 240 V or 480 V, may only be installed in a circuit in which the nominal voltage between any two conductors does not exceed the circuit breaker's voltage rating. A two-pole circuit breaker may not be used for protecting a 3-phase, corner-grounded delta circuit unless the circuit breaker is marked 1Φ -- 3Φ to indicate such suitability. A circuit breaker with a slash rating, such as 120/240 V or 480Y/277 V, may only be installed in a circuit where the nominal voltage of any conductor to ground does not exceed the lower of the two values of the circuit breaker's voltage rating and the nominal voltage between any two conductors does not exceed the higher value of the circuit breaker's voltage rating.
    (2) Feeders and branch circuits over 600 volts, nominal. The following requirements apply to feeders and branch circuits energized at more than 600 volts, nominal:
    (i) Feeder and branch-circuit conductors shall have overcurrent protection in each ungrounded conductor located at the point where the conductor receives its supply or at a location in the circuit determined under engineering supervision;
    (A) Circuit breakers used for overcurrent protection of three-phase circuits shall have a minimum of three overcurrent relays operated from three current transformers. On three-phase, three-wire circuits, an overcurrent relay in the residual circuit of the current transformers may replace one of the phase relays. An overcurrent relay, operated from a current transformer that links all phases of a three-phase, three-wire circuit, may replace the residual relay and one other phase-conductor current transformer. Where the neutral is not grounded on the load side of the circuit, the current transformer may link all three phase conductors and the grounded circuit conductor (neutral); and
    (B) If fuses are used for overcurrent protection, a fuse shall be connected in series with each ungrounded conductor;
    (ii) Each protective device shall be capable of detecting and interrupting all values of current that can occur at its location in excess of its trip setting or melting point;
    (iii) The operating time of the protective device, the available short-circuit current, and the conductor used shall be coordinated to prevent damaging or dangerous temperatures in conductors or conductor insulation under short-circuit conditions; and
    (iv) The following additional requirements apply to feeders only:
    (A) The continuous ampere rating of a fuse may not exceed three times the ampacity of the conductors. The long-time trip element setting of a breaker or the minimum trip setting of an electronically actuated fuse may not exceed six times the ampacity of the conductor. For fire pumps, conductors may be protected for short circuit only; and
    (B) Conductors tapped to a feeder may be protected by the feeder overcurrent device where that overcurrent device also protects the tap conductor.
    (g) Grounding. Paragraphs (g)(1) through (g)(9) of this section contain grounding requirements for systems, circuits, and equipment.
    (1) Systems to be grounded. Systems that supply premises wiring shall be grounded as follows:
    (i) All 3-wire dc systems shall have their neutral conductor grounded;
    (ii) Two-wire dc systems operating at over 50 volts through 300 volts between conductors shall be grounded unless:
    (A) They supply only industrial equipment in limited areas and are equipped with a ground detector;
    (B) They are rectifier-derived from an ac system complying with paragraphs (g)(1)(iii), (g)(1)(iv), and (g)(1)(v) of this section; or
    (C) They are fire-alarm circuits having a maximum current of 0.030 amperes;
    (iii) AC circuits of less than 50 volts shall be grounded if they are installed as overhead conductors outside of buildings or if they are supplied by transformers and the transformer primary supply system is ungrounded or exceeds 150 volts to ground;
    (iv) AC systems of 50 volts to 1000 volts shall be grounded under any of the following conditions, unless exempted by paragraph (g)(1)(v) of this section:
    (A) If the system can be so grounded that the maximum voltage to ground on the ungrounded conductors does not exceed 150 volts;
    (B) If the system is nominally rated three-phase, four-wire wye connected in which the neutral is used as a circuit conductor;
    (C) If the system is nominally rated three-phase, four-wire delta connected in which the midpoint of one phase is used as a circuit conductor; or
    (D) If a service conductor is uninsulated;
    (v) AC systems of 50 volts to 1000 volts are not required to be grounded under any of the following conditions:
    (A) If the system is used exclusively to supply industrial electric furnaces for melting, refining, tempering, and the like;
    (B) If the system is separately derived and is used exclusively for rectifiers supplying only adjustable speed industrial drives;
    (C) If the system is separately derived and is supplied by a transformer that has a primary voltage rating less than 1000 volts, provided all of the following conditions are met:
    (1) The system is used exclusively for control circuits;
    (2) The conditions of maintenance and supervision ensure that only qualified persons will service the installation;
    (3) Continuity of control power is required; and
    (4) Ground detectors are installed on the control system;
    (D) If the system is an isolated power system that supplies circuits in health care facilities; or
    (E) If the system is a high-impedance grounded neutral system in which a grounding impedance, usually a resistor, limits the ground-fault current to a low value for 3-phase ac systems of 480 volts to 1000 volts provided all of the following conditions are met:
    (1) The conditions of maintenance and supervision ensure that only qualified persons will service the installation;
    (2) Continuity of power is required;
    (3) Ground detectors are installed on the system; and
    (4) Line-to-neutral loads are not served.
    (2) Conductor to be grounded. The conductor to be grounded for ac premises wiring systems required to be grounded by paragraph (g)(1) of this section shall be as follows:
    (i) One conductor of a single-phase, two-wire system shall be grounded;
    (ii) The neutral conductor of a single-phase, three-wire system shall be grounded;
    (iii) The common conductor of a multiphase system having one wire common to all phases shall be grounded;
    (iv) One phase conductor of a multiphase system where one phase is grounded shall be grounded; and
    (v) The neutral conductor of a multiphase system in which one phase is used as a neutral conductor shall be grounded.
    (3) Portable and vehicle-mounted generators. (i) The frame of a portable generator need not be grounded and may serve as the grounding electrode for a system supplied by the generator under the following conditions:
    (A) The generator supplies only equipment mounted on the generator or cord- and plug-connected equipment through receptacles mounted on the generator, or both; and
    (B) The noncurrent-carrying metal parts of equipment and the equipment grounding conductor terminals of the receptacles are bonded to the generator frame.
    (ii) The frame of a vehicle need not be grounded and may serve as the grounding electrode for a system supplied by a generator located on the vehicle under the following conditions:
    (A) The frame of the generator is bonded to the vehicle frame;
    (B) The generator supplies only equipment located on the vehicle and cord- and plug-connected equipment through receptacles mounted on the vehicle;
    (C) The noncurrent-carrying metal parts of equipment and the equipment grounding conductor terminals of the receptacles are bonded to the generator frame; and
    (D) The system complies with all other provisions of paragraph (g) of this section.
    (iii) A system conductor that is required to be grounded by the provisions of paragraph (g)(2) of this section shall be bonded to the generator frame where the generator is a component of a separately derived system.
    (4) Grounding connections. (i) For a grounded system, a grounding electrode conductor shall be used to connect both the equipment grounding conductor and the grounded circuit conductor to the grounding electrode. Both the equipment grounding conductor and the grounding electrode conductor shall be connected to the grounded circuit conductor on the supply side of the service disconnecting means or on the supply side of the system disconnecting means or overcurrent devices if the system is separately derived.
    (ii) For an ungrounded service-supplied system, the equipment grounding conductor shall be connected to the grounding electrode conductor at the service equipment. For an ungrounded separately derived system, the equipment grounding conductor shall be connected to the grounding electrode conductor at, or ahead of, the system disconnecting means or overcurrent devices.
    (iii) On extensions of existing branch circuits that do not have an equipment grounding conductor, grounding-type receptacles may be grounded to a grounded cold water pipe near the equipment if the extension was installed before August 13, 2007. When any element of this branch circuit is replaced, the entire branch circuit shall use an equipment grounding conductor that complies with all other provisions of paragraph (g) of this section.
    (5) Grounding path. The path to ground from circuits, equipment, and enclosures shall be permanent, continuous, and effective.
    (6) Supports, enclosures, and equipment to be grounded. (i) Metal cable trays, metal raceways, and metal enclosures for conductors shall be grounded, except that:
    (A) Metal enclosures such as sleeves that are used to protect cable assemblies from physical damage need not be grounded; and
    (B) Metal enclosures for conductors added to existing installations of open wire, knob-and-tube wiring, and nonmetallic-sheathed cable need not be grounded if all of the following conditions are met:
    (1) Runs are less than 7.62 meters (25.0 ft);
    (2) Enclosures are free from probable contact with ground, grounded metal, metal laths, or other conductive materials; and
    (3) Enclosures are guarded against employee contact.
    (ii) Metal enclosures for service equipment shall be grounded.
    (iii) Frames of electric ranges, wall-mounted ovens, counter-mounted cooking units, clothes dryers, and metal outlet or junction boxes that are part of the circuit for these appliances shall be grounded.
    (iv) Exposed noncurrent-carrying metal parts of fixed equipment that may become energized shall be grounded under any of the following conditions:
    (A) If within 2.44 m (8 ft) vertically or 1.52 m (5 ft) horizontally of ground or grounded metal objects and subject to employee contact;
    (B) If located in a wet or damp location and not isolated;
    (C) If in electrical contact with metal;
    (D) If in a hazardous (classified) location;
    (E) If supplied by a metal-clad, metal-sheathed, or grounded metal raceway wiring method; or
    (F) If equipment operates with any terminal at over 150 volts to ground.
    (v) Notwithstanding the provisions of paragraph (g)(6)(iv) of this section, exposed noncurrent-carrying metal parts of the following types of fixed equipment need not be grounded:
    (A) Enclosures for switches or circuit breakers used for other than service equipment and accessible to qualified persons only;
    (B) Electrically heated appliances that are permanently and effectively insulated from ground;
    (C) Distribution apparatus, such as transformer and capacitor cases, mounted on wooden poles, at a height exceeding 2.44 m (8.0 ft) above ground or grade level; and
    (D) Listed equipment protected by a system of double insulation, or its equivalent, and distinctively marked as such.
    (vi) Exposed noncurrent-carrying metal parts of cord- and plug-connected equipment that may become energized shall be grounded under any of the following conditions:
    (A) If in hazardous (classified) locations (see §1910.307);
    (B) If operated at over 150 volts to ground, except for guarded motors and metal frames of electrically heated appliances if the appliance frames are permanently and effectively insulated from ground;
    (C) If the equipment is of the following types:
    (1) Refrigerators, freezers, and air conditioners;
    (2) Clothes-washing, clothes-drying, and dishwashing machines, sump pumps, and electric aquarium equipment;
    (3) Hand-held motor-operated tools, stationary and fixed motor-operated tools, and light industrial motor-operated tools;
    (4) Motor-operated appliances of the following types: hedge clippers, lawn mowers, snow blowers, and wet scrubbers;
    (5) Cord- and plug-connected appliances used in damp or wet locations, or by employees standing on the ground or on metal floors or working inside of metal tanks or boilers;
    (6) Portable and mobile X-ray and associated equipment;
    (7) Tools likely to be used in wet and conductive locations; and
    (8 Portable hand lamps.
    (vii) Notwithstanding the provisions of paragraph (g)(6)(vi) of this section, the following equipment need not be grounded:
    (A) Tools likely to be used in wet and conductive locations if supplied through an isolating transformer with an ungrounded secondary of not over 50 volts; and
    (B) Listed or labeled portable tools and appliances if protected by an approved system of double insulation, or its equivalent, and distinctively marked.
    (7) Nonelectrical equipment. The metal parts of the following nonelectrical equipment shall be grounded: frames and tracks of electrically operated cranes and hoists; frames of nonelectrically driven elevator cars to which electric conductors are attached; hand-operated metal shifting ropes or cables of electric elevators; and metal partitions, grill work, and similar metal enclosures around equipment of over 750 volts between conductors.
    (8) Methods of grounding fixed equipment. (i) Noncurrent-carrying metal parts of fixed equipment, if required to be grounded by this subpart, shall be grounded by an equipment grounding conductor that is contained within the same raceway, cable, or cord, or runs with or encloses the circuit conductors. For dc circuits only, the equipment grounding conductor may be run separately from the circuit conductors.
    (ii) Electric equipment is considered to be effectively grounded if it is secured to, and in electrical contact with, a metal rack or structure that is provided for its support and the metal rack or structure is grounded by the method specified for the noncurrent-carrying metal parts of fixed equipment in paragraph (g)(8)(i) of this section. Metal car frames supported by metal hoisting cables attached to or running over metal sheaves or drums of grounded elevator machines are also considered to be effectively grounded.
    (iii) For installations made before April 16, 1981, electric equipment is also considered to be effectively grounded if it is secured to, and in metallic contact with, the grounded structural metal frame of a building. When any element of this branch circuit is replaced, the entire branch circuit shall use an equipment grounding conductor that complies with all other provisions of paragraph (g) of this section.
    (9) Grounding of systems and circuits of 1000 volts and over (high voltage). If high voltage systems are grounded, they shall comply with all applicable provisions of paragraphs (g)(1) through (g)(8) of this section as supplemented and modified by the following requirements:
    (i) Systems supplying portable or mobile high voltage equipment, other than substations installed on a temporary basis, shall comply with the following:
    (A) The system shall have its neutral grounded through an impedance. If a delta-connected high voltage system is used to supply the equipment, a system neutral shall be derived.
    (B) Exposed noncurrent-carrying metal parts of portable and mobile equipment shall be connected by an equipment grounding conductor to the point at which the system neutral impedance is grounded.
    (C) Ground-fault detection and relaying shall be provided to automatically deenergize any high voltage system component that has developed a ground fault. The continuity of the equipment grounding conductor shall be continuously monitored so as to deenergize automatically the high voltage feeder to the portable equipment upon loss of continuity of the equipment grounding conductor.
    (D) The grounding electrode to which the portable equipment system neutral impedance is connected shall be isolated from and separated in the ground by at least 6.1 m (20.0 ft) from any other system or equipment grounding electrode, and there shall be no direct connection between the grounding electrodes, such as buried pipe, fence, and so forth.
    (ii) All noncurrent-carrying metal parts of portable equipment and fixed equipment, including their associated fences, housings, enclosures, and supporting structures, shall be grounded. However, equipment that is guarded by location and isolated from ground need not be grounded. Additionally, pole-mounted distribution apparatus at a height exceeding 2.44 m (8.0 ft) above ground or grade level need not be grounded.
[46 FR 4056, Jan. 16, 1981, as amended at 73 FR 64205, Oct. 29, 2008]
§1910.305   Wiring methods, components, and equipment for general use.
    (a) Wiring methods. The provisions of this section do not apply to conductors that are an integral part of factory-assembled equipment.
    (1) General requirements. (i) Metal raceways, cable trays, cable armor, cable sheath, enclosures, frames, fittings, and other metal noncurrent-carrying parts that are to serve as grounding conductors, with or without the use of supplementary equipment grounding conductors, shall be effectively bonded where necessary to ensure electrical continuity and the capacity to conduct safely any fault current likely to be imposed on them. Any nonconductive paint, enamel, or similar coating shall be removed at threads, contact points, and contact surfaces or be connected by means of fittings designed so as to make such removal unnecessary.
    (ii) Where necessary for the reduction of electrical noise (electromagnetic interference) of the grounding circuit, an equipment enclosure supplied by a branch circuit may be isolated from a raceway containing circuits supplying only that equipment by one or more listed nonmetallic raceway fittings located at the point of attachment of the raceway to the equipment enclosure. The metal raceway shall be supplemented by an internal insulated equipment grounding conductor installed to ground the equipment enclosure.
    (iii) No wiring systems of any type may be installed in ducts used to transport dust, loose stock, or flammable vapors. No wiring system of any type may be installed in any duct used for vapor removal or for ventilation of commercial-type cooking equipment, or in any shaft containing only such ducts.
    (2) Temporary wiring. Except as specifically modified in this paragraph, all other requirements of this subpart for permanent wiring shall also apply to temporary wiring installations.
    (i) Temporary electrical power and lighting installations of 600 volts, nominal, or less may be used only as follows:
    (A) During and for remodeling, maintenance, or repair of buildings, structures, or equipment, and similar activities;
    (B) For a period not to exceed 90 days for Christmas decorative lighting, carnivals, and similar purposes; or
    (C) For experimental or development work, and during emergencies.
    (ii) Temporary wiring shall be removed immediately upon completion of the project or purpose for which the wiring was installed.
    (iii) Temporary electrical installations of more than 600 volts may be used only during periods of tests, experiments, emergencies, or construction-like activities.
    (iv) The following requirements apply to feeders:
    (A) Feeders shall originate in an approved distribution center.
    (B) Conductors shall be run as multiconductor cord or cable assemblies. However, if installed as permitted in paragraph (a)(2)(i)(C) of this section, and if accessible only to qualified persons, feeders may be run as single insulated conductors.
    (v) The following requirements apply to branch circuits:
    (A) Branch circuits shall originate in an approved power outlet or panelboard.
    (B) Conductors shall be multiconductor cord or cable assemblies or open conductors. If run as open conductors, they shall be fastened at ceiling height every 3.05 m (10.0 ft).
    (C) No branch-circuit conductor may be laid on the floor.
    (D) Each branch circuit that supplies receptacles or fixed equipment shall contain a separate equipment grounding conductor if run as open conductors.
    (vi) Receptacles shall be of the grounding type. Unless installed in a continuous grounded metallic raceway or metallic covered cable, each branch circuit shall contain a separate equipment grounding conductor and all receptacles shall be electrically connected to the grounding conductor.
    (vii) No bare conductors nor earth returns may be used for the wiring of any temporary circuit.
    (viii) Suitable disconnecting switches or plug connectors shall be installed to permit the disconnection of all ungrounded conductors of each temporary circuit. Multiwire branch circuits shall be provided with a means to disconnect simultaneously all ungrounded conductors at the power outlet or panelboard where the branch circuit originated.
    Note to paragraph (a)(2)(viii) of this section. Circuit breakers with their handles connected by approved handle ties are considered a single disconnecting means for the purpose of this requirement.
    (ix) All lamps for general illumination shall be protected from accidental contact or breakage by a suitable fixture or lampholder with a guard. Brass shell, paper-lined sockets, or other metal-cased sockets may not be used unless the shell is grounded.
    (x) Flexible cords and cables shall be protected from accidental damage, as might be caused, for example, by sharp corners, projections, and doorways or other pinch points.
    (xi) Cable assemblies and flexible cords and cables shall be supported in place at intervals that ensure that they will be protected from physical damage. Support shall be in the form of staples, cables ties, straps, or similar type fittings installed so as not to cause damage.
    (3) Cable trays. (i) Only the following wiring methods may be installed in cable tray systems: armored cable; electrical metallic tubing; electrical nonmetallic tubing; fire alarm cables; flexible metal conduit; flexible metallic tubing; instrumentation tray cable; intermediate metal conduit; liquidtight flexible metal conduit; liquidtight flexible nonmetallic conduit; metal-clad cable; mineral-insulated, metal-sheathed cable; multiconductor service-entrance cable; multiconductor underground feeder and branch-circuit cable; multipurpose and communications cables; nonmetallic-sheathed cable; power and control tray cable; power-limited tray cable; optical fiber cables; and other factory-assembled, multiconductor control, signal, or power cables that are specifically approved for installation in cable trays, rigid metal conduit, and rigid nonmetallic conduit.
    (ii) In industrial establishments where conditions of maintenance and supervision assure that only qualified persons will service the installed cable tray system, the following cables may also be installed in ladder, ventilated-trough, or ventilated-channel cable trays:
    (A) Single conductor cable; the cable shall be No. 1/0 or larger and shall be of a type listed and marked on the surface for use in cable trays; where Nos. 1/0 through 4/0 single conductor cables are installed in ladder cable tray, the maximum allowable rung spacing for the ladder cable tray shall be 229 mm (9 in.); where exposed to direct rays of the sun, cables shall be identified as being sunlight resistant;
    (B) Welding cables installed in dedicated cable trays;
    (C) Single conductors used as equipment grounding conductors; these conductors, which may be insulated, covered, or bare, shall be No. 4 or larger; and
    (D) Multiconductor cable, Type MV; where exposed to direct rays of the sun, the cable shall be identified as being sunlight resistant.
    (iii) Metallic cable trays may be used as equipment grounding conductors only where continuous maintenance and supervision ensure that qualified persons will service the installed cable tray system.
    (iv) Cable trays in hazardous (classified) locations may contain only the cable types permitted in such locations. (See §1910.307.)
    (v) Cable tray systems may not be used in hoistways or where subjected to severe physical damage.
    (4) Open wiring on insulators. (i) Open wiring on insulators is only permitted on systems of 600 volts, nominal, or less for industrial or agricultural establishments, indoors or outdoors, in wet or dry locations, where subject to corrosive vapors, and for services.
    (ii) Conductors smaller than No. 8 shall be rigidly supported on noncombustible, nonabsorbent insulating materials and may not contact any other objects. Supports shall be installed as follows:
    (A) Within 152 mm (6 in.) from a tap or splice;
    (B) Within 305 mm (12 in.) of a dead-end connection to a lampholder or receptacle; and
    (C) At intervals not exceeding 1.37 m (4.5 ft), and at closer intervals sufficient to provide adequate support where likely to be disturbed.
    (iii) In dry locations, where not exposed to severe physical damage, conductors may be separately enclosed in flexible nonmetallic tubing. The tubing shall be in continuous lengths not exceeding 4.57 m (15.0 ft) and secured to the surface by straps at intervals not exceeding 1.37 m (4.5 ft).
    (iv) Open conductors shall be separated from contact with walls, floors, wood cross members, or partitions through which they pass by tubes or bushings of noncombustible, nonabsorbent insulating material. If the bushing is shorter than the hole, a waterproof sleeve of nonconductive material shall be inserted in the hole and an insulating bushing slipped into the sleeve at each end in such a manner as to keep the conductors absolutely out of contact with the sleeve. Each conductor shall be carried through a separate tube or sleeve.
    (v) Where open conductors cross ceiling joints and wall studs and are exposed to physical damage (for example, located within 2.13 m (7.0 ft) of the floor), they shall be protected.
    (b) Cabinets, boxes, and fittings -- (1) Conductors entering boxes, cabinets, or fittings. (i) Conductors entering cutout boxes, cabinets, or fittings shall be protected from abrasion, and openings through which conductors enter shall be effectively closed.
    (ii) Unused openings in cabinets, boxes, and fittings shall be effectively closed.
    (iii) Where cable is used, each cable shall be secured to the cabinet, cutout box, or meter socket enclosure. However, where cable with an entirely nonmetallic sheath enters the top of a surface-mounted enclosure through one or more nonflexible raceways not less than 457 mm (18 in.) or more than 3.05 m (10.0 ft) in length, the cable need not be secured to the cabinet, box, or enclosure provided all of the following conditions are met:
    (A) Each cable is fastened within 305 mm (12 in.) of the outer end of the raceway, measured along the sheath;
    (B) The raceway extends directly above the enclosure and does not penetrate a structural ceiling;
    (C) A fitting is provided on each end of the raceway to protect the cable from abrasion, and the fittings remain accessible after installation;
    (D) The raceway is sealed or plugged at the outer end using approved means so as to prevent access to the enclosure through the raceway;
    (E) The cable sheath is continuous through the raceway and extends into the enclosure not less than 6.35 mm (0.25 in.) beyond the fitting;
    (F) The raceway is fastened at its outer end and at other points as necessary; and
    (G) Where installed as conduit or tubing, the allowable cable fill does not exceed that permitted for complete conduit or tubing systems.
    (2) Covers and canopies. (i) All pull boxes, junction boxes, and fittings shall be provided with covers identified for the purpose. If metal covers are used, they shall be grounded. In completed installations, each outlet box shall have a cover, faceplate, or fixture canopy. Covers of outlet boxes having holes through which flexible cord pendants pass shall be provided with bushings designed for the purpose or shall have smooth, well-rounded surfaces on which the cords may bear.
    (ii) Where a fixture canopy or pan is used, any combustible wall or ceiling finish exposed between the edge of the canopy or pan and the outlet box shall be covered with noncombustible material.
    (3) Pull and junction boxes for systems over 600 volts, nominal. In addition to other requirements in this section, the following requirements apply to pull and junction boxes for systems over 600 volts, nominal:
    (i) Boxes shall provide a complete enclosure for the contained conductors or cables.
    (ii) Boxes shall be closed by suitable covers securely fastened in place.
    Note to paragraph (b)(3)(ii) of this section: Underground box covers that weigh over 45.4 kg (100 lbs) meet this requirement.
    (iii) Covers for boxes shall be permanently marked "HIGH VOLTAGE." The marking shall be on the outside of the box cover and shall be readily visible and legible.
    (c) Switches -- (1) Single-throw knife switches. Single-throw knife switches shall be so placed that gravity will not tend to close them. Single-throw knife switches approved for use in the inverted position shall be provided with a locking device that will ensure that the blades remain in the open position when so set.
    (2) Double-throw knife switches. Double-throw knife switches may be mounted so that the throw will be either vertical or horizontal. However, if the throw is vertical, a locking device shall be provided to ensure that the blades remain in the open position when so set.
    (3) Connection of switches. (i) Single-throw knife switches and switches with butt contacts shall be connected so that the blades are deenergized when the switch is in the open position.
    (ii) Single-throw knife switches, molded-case switches, switches with butt contacts, and circuit breakers used as switches shall be connected so that the terminals supplying the load are deenergized when the switch is in the open position. However, blades and terminals supplying the load of a switch may be energized when the switch is in the open position where the switch is connected to circuits or equipment inherently capable of providing a backfeed source of power. For such installations, a permanent sign shall be installed on the switch enclosure or immediately adjacent to open switches that read, "WARNING -- LOAD SIDE TERMINALS MAY BE ENERGIZED BY BACKFEED."
    (4) Faceplates for flush-mounted snap switches. Snap switches mounted in boxes shall have faceplates installed so as to completely cover the opening and seat against the finished surface.
    (5) Grounding. Snap switches, including dimmer switches, shall be effectively grounded and shall provide a means to ground metal faceplates, whether or not a metal faceplate is installed. However, if no grounding means exists within the snap-switch enclosure, or where the wiring method does not include or provide an equipment ground, a snap switch without a grounding connection is permitted for replacement purposes only. Such snap switches shall be provided with a faceplate of nonconducting, noncombustible material if they are located within reach of conducting floors or other conducting surfaces.
    (d) Switchboards and panelboards -- (1) Switchboards with exposed live parts. Switchboards that have any exposed live parts shall be located in permanently dry locations and shall be accessible only to qualified persons.
    (2) Panelboard enclosures. Panelboards shall be mounted in cabinets, cutout boxes, or enclosures designed for the purpose and shall be dead front. However, panelboards other than the dead front externally-operable type are permitted where accessible only to qualified persons.
    (3) Knife switches mounted in switchboards or panelboards. Exposed blades of knife switches mounted in switchboards or panelboards shall be dead when open.
    (e) Enclosures for damp or wet locations -- (1) Cabinets, cutout boxes, fittings, boxes, and panelboard enclosures. Cabinets, cutout boxes, fittings, boxes, and panelboard enclosures in damp or wet locations shall be installed so as to prevent moisture or water from entering and accumulating within the enclosures and shall be mounted so there is at least 6.35-mm (0.25-in.) airspace between the enclosure and the wall or other supporting surface. However, nonmetallic enclosures may be installed without the airspace on a concrete, masonry, tile, or similar surface. The enclosures shall be weatherproof in wet locations.
    (2) Switches, circuit breakers, and switchboards. Switches, circuit breakers, and switchboards installed in wet locations shall be enclosed in weatherproof enclosures.
    (f) Conductors for general wiring -- (1) Insulation. All conductors used for general wiring shall be insulated unless otherwise permitted in this subpart.
    (2) Type. The conductor insulation shall be of a type that is approved for the voltage, operating temperature, and location of use.
    (3) Distinguishable. Insulated conductors shall be distinguishable by appropriate color or other suitable means as being grounded conductors, ungrounded conductors, or equipment grounding conductors.
    (g) Flexible cords and cables -- (1) Use of flexible cords and cables. (i) Flexible cords and cables shall be approved for conditions of use and location.
    (ii) Flexible cords and cables may be used only for:
    (A) Pendants;
    (B) Wiring of fixtures;
    (C) Connection of portable lamps or appliances;
    (D) Portable and mobile signs;
    (E) Elevator cables;
    (F) Wiring of cranes and hoists;
    (G) Connection of stationary equipment to facilitate their frequent interchange;
    (H) Prevention of the transmission of noise or vibration;
    (I) Appliances where the fastening means and mechanical connections are designed to permit removal for maintenance and repair;
    (J) Data processing cables approved as a part of the data processing system;
    (K) Connection of moving parts; and
    (L) Temporary wiring as permitted in paragraph (a)(2) of this section.
    (iii) If used as permitted in paragraphs (g)(1)(ii)(C), (g)(1)(ii)(G), or (g)(1)(ii)(I) of this section, the flexible cord shall be equipped with an attachment plug and shall be energized from an approved receptacle outlet.
    (iv) Unless specifically permitted otherwise in paragraph (g)(1)(ii) of this section, flexible cords and cables may not be used:
    (A) As a substitute for the fixed wiring of a structure;
    (B) Where run through holes in walls, ceilings, or floors;
    (C) Where run through doorways, windows, or similar openings;
    (D) Where attached to building surfaces;
    (E) Where concealed behind building walls, ceilings, or floors; or
    (F) Where installed in raceways, except as otherwise permitted in this subpart.
    (v) Flexible cords used in show windows and showcases shall be Type S, SE, SEO, SEOO, SJ, SJE, SJEO, SJEOO, SJO, SJOO, SJT, SJTO, SJTOO, SO, SOO, ST, STO, or STOO, except for the wiring of chain-supported lighting fixtures and supply cords for portable lamps and other merchandise being displayed or exhibited.
    (2) Identification, splices, and terminations. (i) A conductor of a flexible cord or cable that is used as a grounded conductor or an equipment grounding conductor shall be distinguishable from other conductors. Types S, SC, SCE, SCT, SE, SEO, SEOO, SJ, SJE, SJEO, SJEOO, SJO, SJT, SJTO, SJTOO, SO, SOO, ST, STO, and STOO flexible cords and Types G, G-GC, PPE, and W flexible cables shall be durably marked on the surface at intervals not exceeding 610 mm (24 in.) with the type designation, size, and number of conductors.
    (ii) Flexible cords may be used only in continuous lengths without splice or tap. Hard-service cord and junior hard-service cord No. 14 and larger may be repaired if spliced so that the splice retains the insulation, outer sheath properties, and usage characteristics of the cord being spliced.
    (iii) Flexible cords and cables shall be connected to devices and fittings so that strain relief is provided that will prevent pull from being directly transmitted to joints or terminal screws.
    (h) Portable cables over 600 volts, nominal. This paragraph applies to portable cables used at more than 600 volts, nominal.
    (1) Conductor construction. Multiconductor portable cable for use in supplying power to portable or mobile equipment at over 600 volts, nominal, shall consist of No. 8 or larger conductors employing flexible stranding. However, the minimum size of the insulated ground-check conductor of Type G-GC cables shall be No. 10.
    (2) Shielding. Cables operated at over 2,000 volts shall be shielded for the purpose of confining the voltage stresses to the insulation.
    (3) Equipment grounding conductors. Grounding conductors shall be provided.
    (4) Grounding shields. All shields shall be grounded.
    (5) Minimum bending radii. The minimum bending radii for portable cables during installation and handling in service shall be adequate to prevent damage to the cable.
    (6) Fittings. Connectors used to connect lengths of cable in a run shall be of a type that lock firmly together. Provisions shall be made to prevent opening or closing these connectors while energized. Strain relief shall be provided at connections and terminations.
    (7) Splices. Portable cables may not be operated with splices unless the splices are of the permanent molded, vulcanized, or other approved type.
    (8) Terminations. Termination enclosures shall be suitably marked with a high voltage hazard warning, and terminations shall be accessible only to authorized and qualified employees.
    (i) Fixture wires -- (1) General. Fixture wires shall be approved for the voltage, temperature, and location of use. A fixture wire which is used as a grounded conductor shall be identified.
    (2) Uses permitted. Fixture wires may be used only:
    (i) For installation in lighting fixtures and in similar equipment where enclosed or protected and not subject to bending or twisting in use; or
    (ii) For connecting lighting fixtures to the branch-circuit conductors supplying the fixtures.
    (3) Uses not permitted. Fixture wires may not be used as branch-circuit conductors except as permitted for Class 1 power limited circuits and for fire alarm circuits.
    (j) Equipment for general use -- (1) Lighting fixtures, lampholders, lamps, and receptacles. (i) Fixtures, lampholders, lamps, rosettes, and receptacles may have no live parts normally exposed to employee contact. However, rosettes and cleat-type lampholders and receptacles located at least 2.44 m (8.0 ft) above the floor may have exposed terminals.
    (ii) Handlamps of the portable type supplied through flexible cords shall be equipped with a handle of molded composition or other material identified for the purpose, and a substantial guard shall be attached to the lampholder or the handle. Metal shell, paper-lined lampholders may not be used.
    (iii) Lampholders of the screw-shell type shall be installed for use as lampholders only. Where supplied by a circuit having a grounded conductor, the grounded conductor shall be connected to the screw shell. Lampholders installed in wet or damp locations shall be of the weatherproof type.
    (iv) Fixtures installed in wet or damp locations shall be identified for the purpose and shall be so constructed or installed that water cannot enter or accumulate in wireways, lampholders, or other electrical parts.
    (2) Receptacles, cord connectors, and attachment plugs (caps). (i) All 15- and 20-ampere attachment plugs and connectors shall be constructed so that there are no exposed current-carrying parts except the prongs, blades, or pins. The cover for wire terminations shall be a part that is essential for the operation of an attachment plug or connector (dead-front construction). Attachment plugs shall be installed so that their prongs, blades, or pins are not energized unless inserted into an energized receptacle. No receptacles may be installed so as to require an energized attachment plug as its source of supply.
    (ii) Receptacles, cord connectors, and attachment plugs shall be constructed so that no receptacle or cord connector will accept an attachment plug with a different voltage or current rating than that for which the device is intended. However, a 20-ampere T-slot receptacle or cord connector may accept a 15-ampere attachment plug of the same voltage rating.
    (iii) Nongrounding-type receptacles and connectors may not be used for grounding-type attachment plugs.
    (iv) A receptacle installed in a wet or damp location shall be suitable for the location.
    (v) A receptacle installed outdoors in a location protected from the weather or in other damp locations shall have an enclosure for the receptacle that is weatherproof when the receptacle is covered (attachment plug cap not inserted and receptacle covers closed).
    Note to paragraph (j)(2)(v) of this section. A receptacle is considered to be in a location protected from the weather when it is located under roofed open porches, canopies, marquees, or the like and where it will not be subjected to a beating rain or water runoff.
    (vi) A receptacle installed in a wet location where the product intended to be plugged into it is not attended while in use (for example, sprinkler system controllers, landscape lighting, and holiday lights) shall have an enclosure that is weatherproof with the attachment plug cap inserted or removed.
    (vii) A receptacle installed in a wet location where the product intended to be plugged into it will be attended while in use (for example, portable tools) shall have an enclosure that is weatherproof when the attachment plug cap is removed.
    (3) Appliances. (i) Appliances may have no live parts normally exposed to contact other than parts functioning as open-resistance heating elements, such as the heating elements of a toaster, which are necessarily exposed.
    (ii) Each appliance shall have a means to disconnect it from all ungrounded conductors. If an appliance is supplied by more than one source, the disconnecting means shall be grouped and identified.
    (iii) Each electric appliance shall be provided with a nameplate giving the identifying name and the rating in volts and amperes, or in volts and watts. If the appliance is to be used on a specific frequency or frequencies, it shall be so marked. Where motor overload protection external to the appliance is required, the appliance shall be so marked.
    (iv) Marking shall be located so as to be visible or easily accessible after installation.
    (4) Motors. This paragraph applies to motors, motor circuits, and controllers.
    (i) If specified in paragraph (j)(4) of this section that one piece of equipment shall be "within sight of" another piece of equipment, the piece of equipment shall be visible and not more than 15.24 m (50.0 ft) from the other.
    (ii) An individual disconnecting means shall be provided for each controller. A disconnecting means shall be located within sight of the controller location. However, a single disconnecting means may be located adjacent to a group of coordinated controllers mounted adjacent to each other on a multi-motor continuous process machine. The controller disconnecting means for motor branch circuits over 600 volts, nominal, may be out of sight of the controller, if the controller is marked with a warning label giving the location and identification of the disconnecting means that is to be locked in the open position.
    (iii) The disconnecting means shall disconnect the motor and the controller from all ungrounded supply conductors and shall be so designed that no pole can be operated independently.
    (iv) The disconnecting means shall plainly indicate whether it is in the open (off) or closed (on) position.
    (v) The disconnecting means shall be readily accessible. If more than one disconnect is provided for the same equipment, only one need be readily accessible.
    (vi) An individual disconnecting means shall be provided for each motor, but a single disconnecting means may be used for a group of motors under any one of the following conditions:
    (A) If a number of motors drive several parts of a single machine or piece of apparatus, such as a metal or woodworking machine, crane, or hoist;
    (B) If a group of motors is under the protection of one set of branch-circuit protective devices; or
    (C) If a group of motors is in a single room within sight of the location of the disconnecting means.
    (vii) Motors, motor-control apparatus, and motor branch-circuit conductors shall be protected against overheating due to motor overloads or failure to start, and against short-circuits or ground faults. These provisions do not require overload protection that will stop a motor where a shutdown is likely to introduce additional or increased hazards, as in the case of fire pumps, or where continued operation of a motor is necessary for a safe shutdown of equipment or process and motor overload sensing devices are connected to a supervised alarm.
    (viii) Where live parts of motors or controllers operating at over 150 volts to ground are guarded against accidental contact only by location, and where adjustment or other attendance may be necessary during the operation of the apparatus, suitable insulating mats or platforms shall be provided so that the attendant cannot readily touch live parts unless standing on the mats or platforms.
    (5) Transformers. (i) Paragraph (j)(5) of this section covers the installation of all transformers except the following:
    (A) Current transformers;
    (B) Dry-type transformers installed as a component part of other apparatus;
    (C) Transformers that are an integral part of an X-ray, high frequency, or electrostatic-coating apparatus;
    (D) Transformers used with Class 2 and Class 3 circuits, sign and outline lighting, electric discharge lighting, and power-limited fire-alarm circuits; and
    (E) Liquid-filled or dry-type transformers used for research, development, or testing, where effective safeguard arrangements are provided.
    (ii) The operating voltage of exposed live parts of transformer installations shall be indicated by signs or visible markings on the equipment or structure.
    (iii) Dry-type, high fire point liquid-insulated, and askarel-insulated transformers installed indoors and rated over 35kV shall be in a vault.
    (iv) Oil-insulated transformers installed indoors shall be installed in a vault.
    (v) Combustible material, combustible buildings and parts of buildings, fire escapes, and door and window openings shall be safeguarded from fires that may originate in oil-insulated transformers attached to or adjacent to a building or combustible material.
    (vi) Transformer vaults shall be constructed so as to contain fire and combustible liquids within the vault and to prevent unauthorized access. Locks and latches shall be so arranged that a vault door can be readily opened from the inside.
    (vii) Any pipe or duct system foreign to the electrical installation may not enter or pass through a transformer vault.
    Note to paragraph (j)(5)(vii) of this section. Piping or other facilities provided for vault fire protection, or for transformer cooling, are not considered foreign to the electrical installation.
    (viii) Material may not be stored in transformer vaults.
    (6) Capacitors. (i) All capacitors, except surge capacitors or capacitors included as a component part of other apparatus, shall be provided with an automatic means of draining the stored charge after the capacitor is disconnected from its source of supply.
    (ii) The following requirements apply to capacitors installed on circuits operating at more than 600 volts, nominal:
    (A) Group-operated switches shall be used for capacitor switching and shall be capable of the following:
    (1) Carrying continuously not less than 135 percent of the rated current of the capacitor installation;
    (2) Interrupting the maximum continuous load current of each capacitor, capacitor bank, or capacitor installation that will be switched as a unit;
    (3) Withstanding the maximum inrush current, including contributions from adjacent capacitor installations; and
    (4) Carrying currents due to faults on the capacitor side of the switch;
    (B) A means shall be installed to isolate from all sources of voltage each capacitor, capacitor bank, or capacitor installation that will be removed from service as a unit. The isolating means shall provide a visible gap in the electric circuit adequate for the operating voltage;
    (C) Isolating or disconnecting switches (with no interrupting rating) shall be interlocked with the load interrupting device or shall be provided with prominently displayed caution signs to prevent switching load current; and
    (D) For series capacitors, the proper switching shall be assured by use of at least one of the following:
    (1) Mechanically sequenced isolating and bypass switches;
    (2) Interlocks; or
    (3) Switching procedure prominently displayed at the switching location.
    (7) Storage Batteries. Provisions shall be made for sufficient diffusion and ventilation of gases from storage batteries to prevent the accumulation of explosive mixtures.
§1910.306   Specific purpose equipment and installations.
    (a) Electric signs and outline lighting -- (1) Disconnecting means. (i) Each sign and outline lighting system, or feeder circuit or branch circuit supplying a sign or outline lighting system, shall be controlled by an externally operable switch or circuit breaker that will open all ungrounded conductors. However, a disconnecting means is not required for an exit directional sign located within a building or for cord-connected signs with an attachment plug.
    (ii) Signs and outline lighting systems located within fountains shall have the disconnect located at least 1.52 m (5.0 ft) from the inside walls of the fountain.
    (2) Location. (i) The disconnecting means shall be within sight of the sign or outline lighting system that it controls. Where the disconnecting means is out of the line of sight from any section that may be energized, the disconnecting means shall be capable of being locked in the open position.
    (ii) Signs or outline lighting systems operated by electronic or electromechanical controllers located external to the sign or outline lighting system may have a disconnecting means located within sight of the controller or in the same enclosure with the controller. The disconnecting means shall disconnect the sign or outline lighting system and the controller from all ungrounded supply conductors. It shall be designed so no pole can be operated independently and shall be capable of being locked in the open position.
    (iii) Doors or covers giving access to uninsulated parts of indoor signs or outline lighting exceeding 600 volts and accessible to other than qualified persons shall either be provided with interlock switches to disconnect the primary circuit or shall be so fastened that the use of other than ordinary tools will be necessary to open them.
    (b) Cranes and hoists. This paragraph applies to the installation of electric equipment and wiring used in connection with cranes, monorail hoists, hoists, and all runways.
    (1) Disconnecting means for runway conductors. A disconnecting means shall be provided between the runway contact conductors and the power supply. Such disconnecting means shall consist of a motor-circuit switch, circuit breaker, or molded case switch. The disconnecting means shall open all ungrounded conductors simultaneously and shall be:
    (i) Readily accessible and operable from the ground or floor level;
    (ii) Arranged to be locked in the open position; and
    (iii) Placed within view of the runway contact conductors.
    (2) Disconnecting means for cranes and monorail hoists. (i) Except as provided in paragraph (b)(2)(iv) of this section, a motor-circuit switch, molded case switch, or circuit breaker shall be provided in the leads from the runway contact conductors or other power supply on all cranes and monorail hoists.
    (ii) The disconnecting means shall be capable of being locked in the open position.
    (iii) Means shall be provided at the operating station to open the power circuit to all motors of the crane or monorail hoist where the disconnecting means is not readily accessible from the crane or monorail hoist operating station.
    (iv) The disconnecting means may be omitted where a monorail hoist or hand-propelled crane bridge installation meets all of the following conditions:
    (A) The unit is controlled from the ground or floor level;
    (B) The unit is within view of the power supply disconnecting means; and
    (C) No fixed work platform has been provided for servicing the unit.
    (3) Limit switch. A limit switch or other device shall be provided to prevent the load block from passing the safe upper limit of travel of any hoisting mechanism.
    (4) Clearance. The dimension of the working space in the direction of access to live parts that may require examination, adjustment, servicing, or maintenance while alive shall be a minimum of 762 mm (2.5 ft). Where controls are enclosed in cabinets, the doors shall either open at least 90 degrees or be removable.
    (c) Elevators, dumbwaiters, escalators, moving walks, wheelchair lifts, and stairway chair lifts. The following requirements apply to elevators, dumbwaiters, escalators, moving walks, wheelchair lifts, and stairway chair lifts.
    (1) Disconnecting means. Elevators, dumbwaiters, escalators, moving walks, wheelchair lifts, and stairway chair lifts shall have a single means for disconnecting all ungrounded main power supply conductors for each unit.
    (2) Control panels. Control panels not located in the same space as the drive machine shall be located in cabinets with doors or panels capable of being locked closed.
    (3) Type. The disconnecting means shall be an enclosed externally operable fused motor circuit switch or circuit breaker capable of being locked in the open position. The disconnecting means shall be a listed device.
    (4) Operation. No provision may be made to open or close this disconnecting means from any other part of the premises. If sprinklers are installed in hoistways, machine rooms, or machinery spaces, the disconnecting means may automatically open the power supply to the affected elevators prior to the application of water. No provision may be made to close this disconnecting means automatically (that is, power may only be restored by manual means).
    (5) Location. The disconnecting means shall be located where it is readily accessible to qualified persons.
    (i) On elevators without generator field control, the disconnecting means shall be located within sight of the motor controller. Driving machines or motion and operation controllers not within sight of the disconnecting means shall be provided with a manually operated switch installed in the control circuit adjacent to the equipment in order to prevent starting. Where the driving machine is located in a remote machinery space, a single disconnecting means for disconnecting all ungrounded main power supply conductors shall be provided and be capable of being locked in the open position.
    (ii) On elevators with generator field control, the disconnecting means shall be located within sight of the motor controller for the driving motor of the motor-generator set. Driving machines, motor-generator sets, or motion and operation controllers not within sight of the disconnecting means shall be provided with a manually operated switch installed in the control circuit to prevent starting. The manually operated switch shall be installed adjacent to this equipment. Where the driving machine or the motor-generator set is located in a remote machinery space, a single means for disconnecting all ungrounded main power supply conductors shall be provided and be capable of being locked in the open position.
    (iii) On escalators and moving walks, the disconnecting means shall be installed in the space where the controller is located.
    (iv) On wheelchair lifts and stairway chair lifts, the disconnecting means shall be located within sight of the motor controller.
    (6) Identification and signs. (i) Where there is more than one driving machine in a machine room, the disconnecting means shall be numbered to correspond to the identifying number of the driving machine that they control.
    (ii) The disconnecting means shall be provided with a sign to identify the location of the supply-side overcurrent protective device.
    (7) Single-car and multicar installations. On single-car and multicar installations, equipment receiving electrical power from more than one source shall be provided with a disconnecting means for each source of electrical power. The disconnecting means shall be within sight of the equipment served.
    (8) Warning sign for multiple disconnecting means. A warning sign shall be mounted on or next to the disconnecting means where multiple disconnecting means are used and parts of the controllers remain energized from a source other than the one disconnected. The sign shall be clearly legible and shall read "WARNING -- PARTS OF THE CONTROLLER ARE NOT DEENERGIZED BY THIS SWITCH."
    (9) Interconnection between multicar controllers. A warning sign worded as required in paragraph (c)(8) of this section shall be mounted on or next to the disconnecting means where interconnections between controllers are necessary for the operation of the system on multicar installations that remain energized from a source other than the one disconnected.
    (10) Motor controllers. Motor controllers may be located outside the spaces otherwise required by paragraph (c) of this section, provided they are in enclosures with doors or removable panels capable of being locked closed and the disconnecting means is located adjacent to or is an integral part of the motor controller. Motor controller enclosures for escalators or moving walks may be located in the balustrade on the side located away from the moving steps or moving treadway. If the disconnecting means is an integral part of the motor controller, it shall be operable without opening the enclosure.
    (d) Electric welders -- disconnecting means -- (1) Arc welders. A disconnecting means shall be provided in the supply circuit for each arc welder that is not equipped with a disconnect mounted as an integral part of the welder. The disconnecting means shall be a switch or circuit breaker, and its rating may not be less than that necessary to accommodate overcurrent protection.
    (2) Resistance welders. A switch or circuit breaker shall be provided by which each resistance welder and its control equipment can be disconnected from the supply circuit. The ampere rating of this disconnecting means may not be less than the supply conductor ampacity. The supply circuit switch may be used as the welder disconnecting means where the circuit supplies only one welder.
    (e) Information technology equipment -- (1) Disconnecting means. A means shall be provided to disconnect power to all electronic equipment in an information technology equipment room. There shall also be a similar means to disconnect the power to all dedicated heating, ventilating, and air-conditioning (HVAC) systems serving the room and to cause all required fire/smoke dampers to close.
    (2) Grouping. The control for these disconnecting means shall be grouped and identified and shall be readily accessible at the principal exit doors. A single means to control both the electronic equipment and HVAC system is permitted.
    (3) Exception. Integrated electrical systems covered by §1910.308(g) need not have the disconnecting means required by paragraph (e)(1) of this section.
    (f) X-Ray equipment. This paragraph applies to X-ray equipment.
    (1) Disconnecting means. (i) A disconnecting means shall be provided in the supply circuit. The disconnecting means shall be operable from a location readily accessible from the X-ray control. For equipment connected to a 120-volt branch circuit of 30 amperes or less, a grounding-type attachment plug cap and receptacle of proper rating may serve as a disconnecting means.
    (ii) If more than one piece of equipment is operated from the same high-voltage circuit, each piece or each group of equipment as a unit shall be provided with a high-voltage switch or equivalent disconnecting means. The disconnecting means shall be constructed, enclosed, or located so as to avoid contact by employees with its live parts.
    (2) Control. The following requirements apply to industrial and commercial laboratory equipment.
    (i) Radiographic and fluoroscopic-type equipment shall be effectively enclosed or shall have interlocks that deenergize the equipment automatically to prevent ready access to live current-carrying parts.
    (ii) Diffraction- and irradiation-type equipment shall have a pilot light, readable meter deflection, or equivalent means to indicate when the equipment is energized, unless the equipment or installation is effectively enclosed or is provided with interlocks to prevent access to live current-carrying parts during operation.
    (g) Induction and dielectric heating equipment. This paragraph applies to induction and dielectric heating equipment and accessories for industrial and scientific applications, but not for medical or dental applications or for appliances.
    (1) Guarding and grounding. (i) The converting apparatus (including the dc line) and high-frequency electric circuits (excluding the output circuits and remote-control circuits) shall be completely contained within enclosures of noncombustible material.
    (ii) All panel controls shall be of dead-front construction.
    (iii) Doors or detachable panels shall be employed for internal access. Where doors are used giving access to voltages from 500 to 1000 volts ac or dc, either door locks shall be provided or interlocks shall be installed. Where doors are used giving access to voltages of over 1000 volts ac or dc, either mechanical lockouts with a disconnecting means to prevent access until circuit parts within the cubicle are deenergized, or both door interlocking and mechanical door locks, shall be provided. Detachable panels not normally used for access to such parts shall be fastened in a manner that will make them difficult to remove (for example, by requiring the use of tools).
    (iv) Warning labels or signs that read "DANGER -- HIGH VOLTAGE -- KEEP OUT" shall be attached to the equipment and shall be plainly visible where persons might contact energized parts when doors are opened or closed or when panels are removed from compartments containing over 250 volts ac or dc.
    (v) Induction and dielectric heating equipment shall be protected as follows:
    (A) Protective cages or adequate shielding shall be used to guard work applicators other than induction heating coils.
    (B) Induction heating coils shall be protected by insulation or refractory materials or both.
    (C) Interlock switches shall be used on all hinged access doors, sliding panels, or other such means of access to the applicator, unless the applicator is an induction heating coil at dc ground potential or operating at less than 150 volts ac.
    (D) Interlock switches shall be connected in such a manner as to remove all power from the applicator when any one of the access doors or panels is open.
    (vi) A readily accessible disconnecting means shall be provided by which each heating equipment can be isolated from its supply circuit. The ampere rating of this disconnecting means may not be less than the nameplate current rating of the equipment. The supply circuit disconnecting means is permitted as a heating equipment disconnecting means where the circuit supplies only one piece of equipment.
    (2) Remote control. (i) If remote controls are used for applying power, a selector switch shall be provided and interlocked to provide power from only one control point at a time.
    (ii) Switches operated by foot pressure shall be provided with a shield over the contact button to avoid accidental closing of the switch.
    (h) Electrolytic cells. This paragraph applies to the installation of the electrical components and accessory equipment of electrolytic cells, electrolytic cell lines, and process power supply for the production of aluminum, cadmium, chlorine, copper, fluorine, hydrogen peroxide, magnesium, sodium, sodium chlorate, and zinc. Cells used as a source of electric energy and for electroplating processes and cells used for production of hydrogen are not covered by this paragraph.
    (1) Application. Installations covered by paragraph (h) of this section shall comply with all applicable provisions of this subpart, except as follows:
    (i) Overcurrent protection of electrolytic cell dc process power circuits need not comply with the requirements of §1910.304(f);
    (ii) Equipment located or used within the cell line working zone or associated with the cell line dc power circuits need not comply with the provisions of §1910.304(g); and
    (iii) Electrolytic cells, cell line conductors, cell line attachments, and the wiring of auxiliary equipment and devices within the cell line working zone need not comply with the provisions of §1910.303 or §1910.304(b) and (c).
    (2) Disconnecting means. If more than one dc cell line process power supply serves the same cell line, a disconnecting means shall be provided on the cell line circuit side of each power supply to disconnect it from the cell line circuit. Removable links or removable conductors may be used as the disconnecting means.
    (3) Portable electric equipment. (i) The frames and enclosures of portable electric equipment used within the cell line working zone may not be grounded, unless the cell line circuit voltage does not exceed 200 volts DC or the frames are guarded.
    (ii) Ungrounded portable electric equipment shall be distinctively marked and shall employ plugs and receptacles of a configuration that prevents connection of this equipment to grounding receptacles and that prevents inadvertent interchange of ungrounded and grounded portable electric equipment.
    (4) Power supply circuits and receptacles for portable electric equipment. (i) Circuits supplying power to ungrounded receptacles for hand-held, cord- and plug-connected equipment shall meet the following requirements:
    (A) The circuits shall be electrically isolated from any distribution system supplying areas other than the cell line working zone and shall be ungrounded;
    (B) The circuits shall be supplied through isolating transformers with primaries operating at not more than 600 volts between conductors and protected with proper overcurrent protection;
    (C) The secondary voltage of the isolating transformers may not exceed 300 volts between conductors; and
    (D) All circuits supplied from the secondaries shall be ungrounded and shall have an approved overcurrent device of proper rating in each conductor.
    (ii) Receptacles and their mating plugs for ungrounded equipment may not have provision for a grounding conductor and shall be of a configuration that prevents their use for equipment required to be grounded.
    (iii) Receptacles on circuits supplied by an isolating transformer with an ungrounded secondary:
    (A) Shall have a distinctive configuration;
    (B) Shall be distinctively marked; and
    (C) May not be used in any other location in the facility.
    (5) Fixed and portable electric equipment. (i) The following need not be grounded:
    (A) AC systems supplying fixed and portable electric equipment within the cell line working zone; and
    (B) Exposed conductive surfaces, such as electric equipment housings, cabinets, boxes, motors, raceways and the like that are within the cell line working zone.
    (ii) Auxiliary electric equipment, such as motors, transducers, sensors, control devices, and alarms, mounted on an electrolytic cell or other energized surface shall be connected to the premises wiring systems by any of the following means:
    (A) Multiconductor hard usage or extra hard usage flexible cord;
    (B) Wire or cable in suitable nonmetallic raceways or cable trays; or
    (C) Wire or cable in suitable metal raceways or metal cable trays installed with insulating breaks such that they will not cause a potentially hazardous electrical condition.
    (iii) Fixed electric equipment may be bonded to the energized conductive surfaces of the cell line, its attachments, or auxiliaries. If fixed electric equipment is mounted on an energized conductive surface, it shall be bonded to that surface.
    (6) Auxiliary nonelectrical connections. Auxiliary nonelectrical connections such as air hoses, water hoses, and the like, to an electrolytic cell, its attachments, or auxiliary equipment may not have continuous conductive reinforcing wire, armor, braids, or the like. Hoses shall be of a nonconductive material.
    (7) Cranes and hoists. (i) The conductive surfaces of cranes and hoists that enter the cell line working zone need not be grounded. The portion of an overhead crane or hoist that contacts an energized electrolytic cell or energized attachments shall be insulated from ground.
    (ii) Remote crane or hoist controls that may introduce hazardous electrical conditions into the cell line working zone shall employ one or more of the following systems:
    (A) Isolated and ungrounded control circuit;
    (B) Nonconductive rope operator;
    (C) Pendant pushbutton with nonconductive supporting means and with nonconductive surfaces or ungrounded exposed conductive surfaces; or
    (D) Radio.
    (i) Electrically driven or controlled irrigation machines -- (1) Lightning protection. If an irrigation machine has a stationary point, a grounding electrode system shall be connected to the machine at the stationary point for lightning protection.
    (2) Disconnecting means. (i) The main disconnecting means for a center pivot irrigation machine shall be located at the point of connection of electrical power to the machine or shall be visible and not more than 15.2 m (50 ft) from the machine.
    (ii) The disconnecting means shall be readily accessible and capable of being locked in the open position.
    (iii) A disconnecting means shall be provided for each motor and controller.
    (j) Swimming pools, fountains, and similar installations. This paragraph applies to electric wiring for and equipment in or adjacent to all swimming, wading, therapeutic, and decorative pools and fountains; hydro-massage bathtubs, whether permanently installed or storable; and metallic auxiliary equipment, such as pumps, filters, and similar equipment. Therapeutic pools in health care facilities are exempt from these provisions.
    (1) Receptacles. (i) A single receptacle of the locking and grounding type that provides power for a permanently installed swimming pool recirculating pump motor may be located not less than 1.52 m (5 ft) from the inside walls of a pool. All other receptacles on the property shall be located at least 3.05 m (10 ft) from the inside walls of a pool.
    (ii) Receptacles that are located within 4.57 m (15 ft), or 6.08 m (20 ft) if the installation was built after August 13, 2007, of the inside walls of the pool shall be protected by ground-fault circuit interrupters.
    (iii) Where a pool is installed permanently at a dwelling unit, at least one 125-volt, 15- or 20-ampere receptacle on a general-purpose branch circuit shall be located a minimum of 3.05 m (10 ft) and not more than 6.08 m (20 ft) from the inside wall of the pool. This receptacle shall be located not more than 1.98 m (6.5 ft) above the floor, platform, or grade level serving the pool.
    Note to paragraph (j)(1) of this section: In determining these dimensions, the distance to be measured is the shortest path the supply cord of an appliance connected to the receptacle would follow without piercing a floor, wall, or ceiling of a building or other effective permanent barrier.
    (2) Lighting fixtures, lighting outlets, and ceiling suspended (paddle) fans. (i) In outdoor pool areas, lighting fixtures, lighting outlets, and ceiling-suspended (paddle) fans may not be installed over the pool or over the area extending 1.52 m (5 ft) horizontally from the inside walls of a pool unless no part of the lighting fixture of a ceiling-suspended (paddle) fan is less than 3.66 m (12 ft) above the maximum water level. However, a lighting fixture or lighting outlet that was installed before April 16, 1981, may be located less than 1.52 m (5 ft) measured horizontally from the inside walls of a pool if it is at least 1.52 m (5 ft) above the surface of the maximum water level and is rigidly attached to the existing structure. It shall also be protected by a ground-fault circuit interrupter installed in the branch circuit supplying the fixture.
    (ii) Lighting fixtures and lighting outlets installed in the area extending between 1.52 m (5 ft) and 3.05 m (10 ft) horizontally from the inside walls of a pool shall be protected by a ground-fault circuit interrupter unless installed 1.52 m (5 ft) above the maximum water level and rigidly attached to the structure adjacent to or enclosing the pool.
    (3) Cord- and plug-connected equipment. Flexible cords used with the following equipment may not exceed 0.9 m (3 ft) in length and shall have a copper equipment grounding conductor with a grounding-type attachment plug:
    (i) Cord- and plug-connected lighting fixtures installed within 4.88 m (16 ft) of the water surface of permanently installed pools; and
    (ii) Other cord- and plug-connected, fixed or stationary equipment used with permanently installed pools.
    (4) Underwater equipment. (i) A ground-fault circuit interrupter shall be installed in the branch circuit supplying underwater fixtures operating at more than 15 volts. Equipment installed underwater shall be identified for the purpose.
    (ii) No underwater lighting fixtures may be installed for operation at over 150 volts between conductors.
    (iii) A lighting fixture facing upward shall have the lens adequately guarded to prevent contact by any person.
    (5) Fountains. All electric equipment, including power supply cords, operating at more than 15 volts and used with fountains shall be protected by ground-fault circuit interrupters.
    (k) Carnivals, circuses, fairs, and similar events. This paragraph covers the installation of portable wiring and equipment, including wiring in or on all structures, for carnivals, circuses, exhibitions, fairs, traveling attractions, and similar events.
    (1) Protection of electric equipment. Electric equipment and wiring methods in or on rides, concessions, or other units shall be provided with mechanical protection where such equipment or wiring methods are subject to physical damage.
    (2) Installation. (i) Services shall be installed in accordance with applicable requirements of this subpart, and, in addition, shall comply with the following:
    (A) Service equipment may not be installed in a location that is accessible to unqualified persons, unless the equipment is lockable; and
    (B) Service equipment shall be mounted on solid backing and installed so as to be protected from the weather, unless the equipment is of weatherproof construction.
    (ii) Amusement rides and amusement attractions shall be maintained not less than 4.57 m (15 ft) in any direction from overhead conductors operating at 600 volts or less, except for the conductors supplying the amusement ride or attraction. Amusement rides or attractions may not be located under or within 4.57 m (15 ft) horizontally of conductors operating in excess of 600 volts.
    (iii) Flexible cords and cables shall be listed for extra-hard usage. When used outdoors, flexible cords and cables shall also be listed for wet locations and shall be sunlight resistant.
    (iv) Single conductor cable shall be size No. 2 or larger.
    (v) Open conductors are prohibited except as part of a listed assembly or festoon lighting installed in accordance with §1910.304(c).
    (vi) Flexible cords and cables shall be continuous without splice or tap between boxes or fittings. Cord connectors may not be laid on the ground unless listed for wet locations. Connectors and cable connections may not be placed in audience traffic paths or within areas accessible to the public unless guarded.
    (vii) Wiring for an amusement ride, attraction, tent, or similar structure may not be supported by another ride or structure unless specifically identified for the purpose.
    (viii) Flexible cords and cables run on the ground, where accessible to the public, shall be covered with approved nonconductive mats. Cables and mats shall be arranged so as not to present a tripping hazard.
    (ix) A box or fitting shall be installed at each connection point, outlet, switch point, or junction point.
    (3) Inside tents and concessions. Electrical wiring for temporary lighting, where installed inside of tents and concessions, shall be securely installed, and, where subject to physical damage, shall be provided with mechanical protection. All temporary lamps for general illumination shall be protected from accidental breakage by a suitable fixture or lampholder with a guard.
    (4) Portable distribution and termination boxes. Employers may only use portable distribution and termination boxes that meet the following requirements:
    (i) Boxes shall be designed so that no live parts are exposed to accidental contact. Where installed outdoors, the box shall be of weatherproof construction and mounted so that the bottom of the enclosure is not less than 152 mm (6 in.) above the ground;
    (ii) Busbars shall have an ampere rating not less than the overcurrent device supplying the feeder supplying the box. Busbar connectors shall be provided where conductors terminate directly on busbars;
    (iii) Receptacles shall have overcurrent protection installed within the box. The overcurrent protection may not exceed the ampere rating of the receptacle, except as permitted in §1910.305(j)(4) for motor loads;
    (iv) Where single-pole connectors are used, they shall comply with the following:
    (A) Where ac single-pole portable cable connectors are used, they shall be listed and of the locking type. Where paralleled sets of current-carrying single-pole separable connectors are provided as input devices, they shall be prominently labeled with a warning indicating the presence of internal parallel connections. The use of single-pole separable connectors shall comply with at least one of the following conditions:
    (1) Connection and disconnection of connectors are only possible where the supply connectors are interlocked to the source and it is not possible to connect or disconnect connectors when the supply is energized; or
    (2) Line connectors are of the listed sequential-interlocking type so that load connectors are connected in the following sequence:
    (i) Equipment grounding conductor connection;
    (ii) Grounded circuit-conductor connection, if provided; and
    (iii) Ungrounded conductor connection; and so that disconnection is in the reverse order; or
    (3) A caution notice is provided adjacent to the line connectors indicating that plug connection must be in the following sequence:
    (i) Equipment grounding conductor connection;
    (ii) Grounded circuit-conductor connection, if provided; and
    (iii) Ungrounded conductor connection; and indicating that disconnection is in the reverse order; and
    (B) Single-pole separable connectors used in portable professional motion picture and television equipment may be interchangeable for ac or dc use or for different current ratings on the same premises only if they are listed for ac/dc use and marked to identify the system to which they are connected;
    (v) Overcurrent protection of equipment and conductors shall be provided; and
    (vi) The following equipment connected to the same source shall be bonded:
    (A) Metal raceways and metal sheathed cable;
    (B) Metal enclosures of electrical equipment; and
    (C) Metal frames and metal parts of rides, concessions, trailers, trucks, or other equipment that contain or support electrical equipment.
    (5) Disconnecting means. (i) Each ride and concession shall be provided with a fused disconnect switch or circuit breaker located within sight and within 1.83 m (6 ft) of the operator's station.
    (ii) The disconnecting means shall be readily accessible to the operator, including when the ride is in operation.
    (iii) Where accessible to unqualified persons, the enclosure for the switch or circuit breaker shall be of the lockable type.
    (iv) A shunt trip device that opens the fused disconnect or circuit breaker when a switch located in the ride operator's console is closed is a permissible method of opening the circuit.
§1910.307   Hazardous (classified) locations.
    (a) Scope -- (1) Applicability. This section covers the requirements for electric equipment and wiring in locations that are classified depending on the properties of the flammable vapors, liquids or gases, or combustible dusts or fibers that may be present therein and the likelihood that a flammable or combustible concentration or quantity is present. Hazardous (classified) locations may be found in occupancies such as, but not limited to, the following: aircraft hangars, gasoline dispensing and service stations, bulk storage plants for gasoline or other volatile flammable liquids, paint-finishing process plants, health care facilities, agricultural or other facilities where excessive combustible dusts may be present, marinas, boat yards, and petroleum and chemical processing plants. Each room, section or area shall be considered individually in determining its classification.
    (2) Classifications. (i) These hazardous (classified) locations are assigned the following designations:
    (A) Class I, Division 1
    (B) Class I, Division 2
    (C) Class I, Zone 0
    (D) Class I, Zone 1
    (E) Class I, Zone 2
    (F) Class II, Division 1
    (G) Class II, Division 2
    (H) Class III, Division 1
    (I) Class III, Division 2
    (ii) For definitions of these locations, see §1910.399.
    (3) Other sections of this subpart. All applicable requirements in this subpart apply to hazardous (classified) locations unless modified by provisions of this section.
    (4) Division and zone classification. In Class I locations, an installation must be classified as using the division classification system meeting paragraphs (c), (d), (e), and (f) of this section or using the zone classification system meeting paragraph (g) of this section. In Class II and Class III locations, an installation must be classified using the division classification system meeting paragraphs (c), (d), (e), and (f) of this section.
    (b) Documentation. All areas designated as hazardous (classified) locations under the Class and Zone system and areas designated under the Class and Division system established after August 13, 2007 shall be properly documented. This documentation shall be available to those authorized to design, install, inspect, maintain, or operate electric equipment at the location.
    (c) Electrical installations. Equipment, wiring methods, and installations of equipment in hazardous (classified) locations shall be intrinsically safe, approved for the hazardous (classified) location, or safe for the hazardous (classified) location. Requirements for each of these options are as follows:
    (1) Intrinsically safe. Equipment and associated wiring approved as intrinsically safe is permitted in any hazardous (classified) location for which it is approved;
    (2) Approved for the hazardous (classified) location. (i) Equipment shall be approved not only for the class of location, but also for the ignitable or combustible properties of the specific gas, vapor, dust, or fiber that will be present.
    Note to paragraph (c)(2)(i) of this section: NFPA 70, the National Electrical Code, lists or defines hazardous gases, vapors, and dusts by "Groups" characterized by their ignitable or combustible properties.
    (ii) Equipment shall be marked to show the class, group, and operating temperature or temperature range, based on operation in a 40-degree C ambient, for which it is approved. The temperature marking may not exceed the ignition temperature of the specific gas or vapor to be encountered. However, the following provisions modify this marking requirement for specific equipment:
    (A) Equipment of the nonheat-producing type, such as junction boxes, conduit, and fittings, and equipment of the heat-producing type having a maximum temperature not more than 100 °C (212 °F) need not have a marked operating temperature or temperature range;
    (B) Fixed lighting fixtures marked for use in Class I, Division 2 or Class II, Division 2 locations only need not be marked to indicate the group;
    (C) Fixed general-purpose equipment in Class I locations, other than lighting fixtures, that is acceptable for use in Class I, Division 2 locations need not be marked with the class, group, division, or operating temperature;
    (D) Fixed dust-tight equipment, other than lighting fixtures, that is acceptable for use in Class II, Division 2 and Class III locations need not be marked with the class, group, division, or operating temperature; and
    (E) Electric equipment suitable for ambient temperatures exceeding 40 °C (104 °F) shall be marked with both the maximum ambient temperature and the operating temperature or temperature range at that ambient temperature; and
    (3) Safe for the hazardous (classified) location. Equipment that is safe for the location shall be of a type and design that the employer demonstrates will provide protection from the hazards arising from the combustibility and flammability of vapors, liquids, gases, dusts, or fibers involved.
    Note to paragraph (c)(3) of this section: The National Electrical Code, NFPA 70, contains guidelines for determining the type and design of equipment and installations that will meet this requirement. Those guidelines address electric wiring, equipment, and systems installed in hazardous (classified) locations and contain specific provisions for the following: wiring methods, wiring connections; conductor insulation, flexible cords, sealing and drainage, transformers, capacitors, switches, circuit breakers, fuses, motor controllers, receptacles, attachment plugs, meters, relays, instruments, resistors, generators, motors, lighting fixtures, storage battery charging equipment, electric cranes, electric hoists and similar equipment, utilization equipment, signaling systems, alarm systems, remote control systems, local loud speaker and communication systems, ventilation piping, live parts, lightning surge protection, and grounding.
    (d) Conduits. All conduits shall be threaded and shall be made wrench-tight. Where it is impractical to make a threaded joint tight, a bonding jumper shall be utilized.
    (e) Equipment in Division 2 locations. Equipment that has been approved for a Division 1 location may be installed in a Division 2 location of the same class and group. General-purpose equipment or equipment in general-purpose enclosures may be installed in Division 2 locations if the employer can demonstrate that the equipment does not constitute a source of ignition under normal operating conditions.
    (f) Protection techniques. The following are acceptable protection techniques for electric and electronic equipment in hazardous (classified) locations.
    (1) Explosionproof apparatus. This protection technique is permitted for equipment in the Class I, Division 1 and 2 locations for which it is approved.
    (2) Dust ignitionproof. This protection technique is permitted for equipment in the Class II, Division 1 and 2 locations for which it is approved.
    (3) Dust-tight. This protection technique is permitted for equipment in the Class II, Division 2 and Class III locations for which it is approved.
    (4) Purged and pressurized. This protection technique is permitted for equipment in any hazardous (classified) location for which it is approved.
    (5) Nonincendive circuit. This protection technique is permitted for equipment in Class I, Division 2; Class II, Division 2; or Class III, Division 1or 2 locations.
    (6) Nonincendive equipment. This protection technique is permitted for equipment in Class I, Division 2; Class II, Division 2; or Class III, Division 1 or 2 locations.
    (7) Nonincendive component. This protection technique is permitted for equipment in Class I, Division 2; Class II, Division 2; or Class III, Division 1 or 2 locations.
    (8) Oil immersion. This protection technique is permitted for current-interrupting contacts in Class I, Division 2 locations as described in the Subpart.
    (9) Hermetically sealed. This protection technique is permitted for equipment in Class I, Division 2; Class II, Division 2; and Class III, Division 1 or 2 locations.
    (10) Other protection techniques. Any other protection technique that meets paragraph (c) of this section is acceptable in any hazardous (classified) location.
    (g) Class I, Zone 0, 1, and 2 locations -- (1) Scope. Employers may use the zone classification system as an alternative to the division classification system for electric and electronic equipment and wiring for all voltage in Class I, Zone 0, Zone 1, and Zone 2 hazardous (classified) locations where fire or explosion hazards may exist due to flammable gases, vapors, or liquids.
    (2) Location and general requirements. (i) Locations shall be classified depending on the properties of the flammable vapors, liquids, or gases that may be present and the likelihood that a flammable or combustible concentration or quantity is present. Where pyrophoric materials are the only materials used or handled, these locations need not be classified.
    (ii) Each room, section, or area shall be considered individually in determining its classification.
    (iii) All threaded conduit shall be threaded with an NPT (National (American) Standard Pipe Taper) standard conduit cutting die that provides 3⁄4 -in. taper per foot. The conduit shall be made wrench tight to prevent sparking when fault current flows through the conduit system and to ensure the explosionproof or flameproof integrity of the conduit system where applicable.
    (iv) Equipment provided with threaded entries for field wiring connection shall be installed in accordance with paragraph (g)(2)(iv)(A) or (g)(2)(iv)(B) of this section.
    (A) For equipment provided with threaded entries for NPT threaded conduit or fittings, listed conduit, conduit fittings, or cable fittings shall be used.
    (B) For equipment with metric threaded entries, such entries shall be identified as being metric, or listed adaptors to permit connection to conduit of NPT-threaded fittings shall be provided with the equipment. Adapters shall be used for connection to conduit or NPT-threaded fittings.
    (3) Protection techniques. One or more of the following protection techniques shall be used for electric and electronic equipment in hazardous (classified) locations classified under the zone classification system.
    (i) Flameproof "d" -- This protection technique is permitted for equipment in the Class I, Zone 1 locations for which it is approved.
    (ii) Purged and pressurized -- This protection technique is permitted for equipment in the Class I, Zone 1 or Zone 2 locations for which it is approved.
    (iii) Intrinsic safety -- This protection technique is permitted for equipment in the Class I, Zone 0 or Zone 1 locations for which it is approved.
    (iv) Type of protection "n" -- This protection technique is permitted for equipment in the Class I, Zone 2 locations for which it is approved. Type of protection "n" is further subdivided into nA, nC, and nR.
    (v) Oil Immersion "o" -- This protection technique is permitted for equipment in the Class I, Zone 1 locations for which it is approved.
    (vi) Increased safety "e" -- This protection technique is permitted for equipment in the Class I, Zone 1 locations for which it is approved.
    (vii) Encapsulation "m" -- This protection technique is permitted for equipment in the Class I, Zone 1 locations for which it is approved.
    (viii) Powder Filling "q" -- This protection technique is permitted for equipment in the Class I, Zone 1 locations for which it is approved.
    (4) Special precaution. Paragraph (g) of this section requires equipment construction and installation that will ensure safe performance under conditions of proper use and maintenance.
    (i) Classification of areas and selection of equipment and wiring methods shall be under the supervision of a qualified registered professional engineer.
    (ii) In instances of areas within the same facility classified separately, Class I, Zone 2 locations may abut, but not overlap, Class I, Division 2 locations. Class I, Zone 0 or Zone 1 locations may not abut Class I, Division 1 or Division 2 locations.
    (iii) A Class I, Division 1 or Division 2 location may be reclassified as a Class I, Zone 0, Zone 1, or Zone 2 location only if all of the space that is classified because of a single flammable gas or vapor source is reclassified.
    Note to paragraph (g)(4) of this section: Low ambient conditions require special consideration. Electric equipment depending on the protection techniques described by paragraph (g)(3)(i) of this section may not be suitable for use at temperatures lower than −20 °C (−4 °F) unless they are approved for use at lower temperatures. However, at low ambient temperatures, flammable concentrations of vapors may not exist in a location classified Class I, Zone 0, 1, or 2 at normal ambient temperature.
    (5) Listing and marking. (i) Equipment that is listed for a Zone 0 location may be installed in a Zone 1 or Zone 2 location of the same gas or vapor. Equipment that is listed for a Zone 1 location may be installed in a Zone 2 location of the same gas or vapor.
    (ii) Equipment shall be marked in accordance with paragraph (g)(5)(ii)(A) and (g)(5)(ii)(B) of this section, except as provided in (g)(5)(ii)(C).
    (A) Equipment approved for Class I, Division 1 or Class 1, Division 2 shall, in addition to being marked in accordance with (c)(2)(ii), be marked with the following:
    (1) Class I, Zone 1 or Class I, Zone 2 (as applicable);
    (2) Applicable gas classification groups; and
    (3) Temperature classification; or
    (B) Equipment meeting one or more of the protection techniques described in paragraph (g)(3) of this section shall be marked with the following in the order shown:
    (1) Class, except for intrinsically safe apparatus;
    (2) Zone, except for intrinsically safe apparatus;
    (3) Symbol "AEx;"
    (4) Protection techniques;
    (5) Applicable gas classification groups; and
    (6) Temperature classification, except for intrinsically safe apparatus.
    Note to paragraph (g)(5)(ii)(B) of this section: An example of such a required marking is "Class I, Zone 0, AEx ia IIC T6." See Figure S-1 for an explanation of this marking.
    (C) Equipment that the employer demonstrates will provide protection from the hazards arising from the flammability of the gas or vapor and the zone of location involved and will be recognized as providing such protection by employees need not be marked.
    Note to paragraph (g)(5)(ii)(C) of this section: The National Electrical Code, NFPA 70, contains guidelines for determining the type and design of equipment and installations that will meet this provision.

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§1910.308   Special systems.
    (a) Systems over 600 volts, nominal. This paragraph covers the general requirements for all circuits and equipment operated at over 600 volts.
    (1) Aboveground wiring methods. (i) Aboveground conductors shall be installed in rigid metal conduit, in intermediate metal conduit, in electrical metallic tubing, in rigid nonmetallic conduit, in cable trays, as busways, as cablebus, in other identified raceways, or as open runs of metal-clad cable suitable for the use and purpose. In locations accessible to qualified persons only, open runs of Type MV cables, bare conductors, and bare busbars are also permitted. Busbars shall be either copper or aluminum. Open runs of insulated wires and cables having a bare lead sheath or a braided outer covering shall be supported in a manner designed to prevent physical damage to the braid or sheath.
    (ii) Conductors emerging from the ground shall be enclosed in approved raceways.
    (2) Braid-covered insulated conductors -- open installations. The braid on open runs of braid-covered insulated conductors shall be flame retardant or shall have a flame-retardant saturant applied after installation. This treated braid covering shall be stripped back a safe distance at conductor terminals, according to the operating voltage.
    (3) Insulation shielding. (i) Metallic and semiconductor insulation shielding components of shielded cables shall be removed for a distance dependent on the circuit voltage and insulation. Stress reduction means shall be provided at all terminations of factory-applied shielding.
    (ii) Metallic shielding components such as tapes, wires, or braids, or combinations thereof, and their associated conducting and semiconducting components shall be grounded.
    (4) Moisture or mechanical protection for metal-sheathed cables. Where cable conductors emerge from a metal sheath and where protection against moisture or physical damage is necessary, the insulation of the conductors shall be protected by a cable sheath terminating device.
    (5) Interrupting and isolating devices. (i) Circuit breaker installations located indoors shall consist of metal-enclosed units or fire-resistant cell-mounted units. In locations accessible only to qualified employees, open mounting of circuit breakers is permitted. A means of indicating the open and closed position of circuit breakers shall be provided.
    (ii) Where fuses are used to protect conductors and equipment, a fuse shall be placed in each ungrounded conductor. Two power fuses may be used in parallel to protect the same load, if both fuses have identical ratings, and if both fuses are installed in an identified common mounting with electrical connections that will divide the current equally. Power fuses of the vented type may not be used indoors, underground, or in metal enclosures unless identified for the use.
    (iii) Fused cutouts installed in buildings or transformer vaults shall be of a type identified for the purpose. Distribution cutouts may not be used indoors, underground, or in metal enclosures. They shall be readily accessible for fuse replacement.
    (iv) Where fused cutouts are not suitable to interrupt the circuit manually while carrying full load, an approved means shall be installed to interrupt the entire load. Unless the fused cutouts are interlocked with the switch to prevent opening of the cutouts under load, a conspicuous sign shall be placed at such cutouts reading: "WARNING -- DO NOT OPERATE UNDER LOAD."
    (v) Suitable barriers or enclosures shall be provided to prevent contact with nonshielded cables or energized parts of oil-filled cutouts.
    (vi) Load interrupter switches may be used only if suitable fuses or circuits are used in conjunction with these devices to interrupt fault currents.
    (A) Where these devices are used in combination, they shall be coordinated electrically so that they will safely withstand the effects of closing, carrying, or interrupting all possible currents up to the assigned maximum short-circuit rating.
    (B) Where more than one switch is installed with interconnected load terminals to provide for alternate connection to different supply conductors, each switch shall be provided with a conspicuous sign reading: "WARNING -- SWITCH MAY BE ENERGIZED BY BACKFEED."
    (vii) A means (for example, a fuseholder and fuse designed for the purpose) shall be provided to completely isolate equipment for inspection and repairs. Isolating means that are not designed to interrupt the load current of the circuit shall be either interlocked with an approved circuit interrupter or provided with a sign warning against opening them under load.
    (6) Mobile and portable equipment. (i) A metallic enclosure shall be provided on the mobile machine for enclosing the terminals of the power cable. The enclosure shall include provisions for a solid connection for the grounding terminal to effectively ground the machine frame. The method of cable termination used shall prevent any strain or pull on the cable from stressing the electrical connections. The enclosure shall have provision for locking so only authorized qualified persons may open it and shall be marked with a sign warning of the presence of energized parts.
    (ii) All energized switching and control parts shall be enclosed in effectively grounded metal cabinets or enclosures. Circuit breakers and protective equipment shall have the operating means projecting through the metal cabinet or enclosure so these units can be reset without locked doors being opened. Enclosures and metal cabinets shall be locked so that only authorized qualified persons have access and shall be marked with a sign warning of the presence of energized parts. Collector ring assemblies on revolving-type machines (shovels, draglines, etc.) shall be guarded.
    (7) Tunnel installations. This paragraph applies to installation and use of high-voltage power distribution and utilization equipment that is portable or mobile, such as substations, trailers, cars, mobile shovels, draglines, hoists, drills, dredges, compressors, pumps, conveyors, and underground excavators.
    (i) Conductors in tunnels shall be installed in one or more of the following:
    (A) Metal conduit or other metal raceway;
    (B) Type MC cable; or
    (C) Other approved multiconductor cable.
    (ii) Multiconductor portable cable may supply mobile equipment.
    (iii) Conductors and cables shall also be so located or guarded as to protect them from physical damage. An equipment grounding conductor shall be run with circuit conductors inside the metal raceway or inside the multiconductor cable jacket. The equipment grounding conductor may be insulated or bare.
    (iv) Bare terminals of transformers, switches, motor controllers, and other equipment shall be enclosed to prevent accidental contact with energized parts.
    (v) Enclosures for use in tunnels shall be drip-proof, weatherproof, or submersible as required by the environmental conditions.
    (vi) Switch or contactor enclosures may not be used as junction boxes or raceways for conductors feeding through or tapping off to other switches, unless special designs are used to provide adequate space for this purpose.
    (vii) A disconnecting means that simultaneously opens all ungrounded conductors shall be installed at each transformer or motor location.
    (viii) All nonenergized metal parts of electric equipment and metal raceways and cable sheaths shall be effectively grounded and bonded to all metal pipes and rails at the portal and at intervals not exceeding 305 m (1000 ft) throughout the tunnel.
    (b) Emergency power systems. This paragraph applies to circuits, systems, and equipment intended to supply power for illumination and special loads in the event of failure of the normal supply.
    (1) Wiring methods. Emergency circuit wiring shall be kept entirely independent of all other wiring and equipment and may not enter the same raceway, cable, box, or cabinet or other wiring except either where common circuit elements suitable for the purpose are required, or for transferring power from the normal to the emergency source.
    (2) Emergency illumination. Emergency illumination shall include all required means of egress lighting, illuminated exit signs, and all other lights necessary to provide illumination. Where emergency lighting is necessary, the system shall be so arranged that the failure of any individual lighting element, such as the burning out of a light bulb, cannot leave any space in total darkness.
    (3) Signs. (i) A sign shall be placed at the service entrance equipment indicating the type and location of on-site emergency power sources. However, a sign is not required for individual unit equipment.
    (ii) Where the grounded circuit conductor connected to the emergency source is connected to a grounding electrode conductor at a location remote from the emergency source, there shall be a sign at the grounding location that shall identify all emergency and normal sources connected at that location.
    (c) Class 1, Class 2, and Class 3 remote control, signaling, and power-limited circuits -- (1) Classification. Class 1, Class 2, and Class 3 remote control, signaling, or power-limited circuits are characterized by their usage and electrical power limitation that differentiates them from light and power circuits. These circuits are classified in accordance with their respective voltage and power limitations as summarized in paragraphs (c)(1)(i) through (c)(1)(iii) of this section.
    (i) A Class 1 power-limited circuit shall be supplied from a source having a rated output of not more than 30 volts and 1000 volt-amperes.
    (ii) A Class 1 remote control circuit or a Class 1 signaling circuit shall have a voltage not exceeding 600 volts; however, the power output of the source need not be limited.
    (iii) The power source for a Class 2 or Class 3 circuit shall be listed equipment marked as a Class 2 or Class 3 power source, except as follows:
    (A) Thermocouples do not require listing as a Class 2 power source; and
    (B) A dry cell battery is considered an inherently limited Class 2 power source, provided the voltage is 30 volts or less and the capacity is less than or equal to that available from series-connected No. 6 carbon zinc cells.
    (2) Marking. A Class 2 or Class 3 power supply unit shall be durably marked where plainly visible to indicate the class of supply and its electrical rating.
    (3) Separation from conductors of other circuits. Cables and conductors of Class 2 and Class 3 circuits may not be placed in any cable, cable tray, compartment, enclosure, manhole, outlet box, device box, raceway, or similar fitting with conductors of electric light, power, Class 1, nonpower-limited fire alarm circuits, and medium power network-powered broadband communications cables unless a barrier or other equivalent form of protection against contact is employed.
    (d) Fire alarm systems -- (1) Classifications. Fire alarm circuits shall be classified either as nonpower limited or power limited.
    (2) Power sources. The power sources for use with fire alarm circuits shall be either power limited or nonpower limited as follows:
    (i) The power source of nonpower-limited fire alarm (NPLFA) circuits shall have an output voltage of not more than 600 volts, nominal; and
    (ii) The power source for a power-limited fire alarm (PLFA) circuit shall be listed equipment marked as a PLFA power source.
    (3) Separation from conductors of other circuits. (i) Nonpower-limited fire alarm circuits and Class 1 circuits may occupy the same enclosure, cable, or raceway provided all conductors are insulated for maximum voltage of any conductor within the enclosure, cable, or raceway. Power supply and fire alarm circuit conductors are permitted in the same enclosure, cable, or raceway only if connected to the same equipment.
    (ii) Power-limited circuit cables and conductors may not be placed in any cable, cable tray, compartment, enclosure, outlet box, raceway, or similar fitting with conductors of electric light, power, Class 1, nonpower-limited fire alarm circuit conductors, or medium power network-powered broadband communications circuits.
    (iii) Power-limited fire alarm circuit conductors shall be separated at least 50.8 mm (2 in.) from conductors of any electric light, power, Class 1, nonpower-limited fire alarm, or medium power network-powered broadband communications circuits unless a special and equally protective method of conductor separation is employed.
    (iv) Conductors of one or more Class 2 circuits are permitted within the same cable, enclosure, or raceway with conductors of power-limited fire alarm circuits provided that the insulation of Class 2 circuit conductors in the cable, enclosure, or raceway is at least that needed for the power-limited fire alarm circuits.
    (4) Identification. Fire alarm circuits shall be identified at terminal and junction locations in a manner that will prevent unintentional interference with the signaling circuit during testing and servicing. Power-limited fire alarm circuits shall be durably marked as such where plainly visible at terminations.
    (e) Communications systems. This paragraph applies to central-station-connected and non-central-station-connected telephone circuits, radio and television receiving and transmitting equipment, including community antenna television and radio distribution systems, telegraph, district messenger, and outside wiring for fire and burglar alarm, and similar central station systems. These installations need not comply with the provisions of §1910.303 through §1910.308(d), except for §§1910.304(c)(1) and 1910.307.
    (1) Protective devices. (i) A listed primary protector shall be provided on each circuit run partly or entirely in aerial wire or aerial cable not confined within a block.
    (ii) A listed primary protector shall be also provided on each aerial or underground circuit when the location of the circuit within the block containing the building served allows the circuit to be exposed to accidental contact with electric light or power conductors operating at over 300 volts to ground.
    (iii) In addition, where there exists a lightning exposure, each interbuilding circuit on premises shall be protected by a listed primary protector at each end of the interbuilding circuit.
    (2) Conductor location. (i) Lead-in or aerial-drop cables from a pole or other support, including the point of initial attachment to a building or structure, shall be kept away from electric light, power, Class 1, or nonpower-limited fire alarm circuit conductors so as to avoid the possibility of accidental contact.
    (ii) A separation of at least 1.83 m (6 ft) shall be maintained between communications wires and cables on buildings and lightning conductors.
    (iii) Where communications wires and cables and electric light or power conductors are supported by the same pole or run parallel to each other in-span, the following conditions shall be met:
    (A) Where practicable, communication wires and cables on poles shall be located below the electric light or power conductors; and
    (B) Communications wires and cables may not be attached to a crossarm that carries electric light or power conductors.
    (iv) Indoor communications wires and cables shall be separated at least 50.8 mm (2 in.) from conductors of any electric light, power, Class 1, nonpower-limited fire alarm, or medium power network-powered broadband communications circuits, unless a special and equally protective method of conductor separation, identified for the purpose, is employed.
    (3) Equipment location. Outdoor metal structures supporting antennas, as well as self-supporting antennas such as vertical rods or dipole structures, shall be located as far away from overhead conductors of electric light and power circuits of over 150 volts to ground as necessary to prevent the antenna or structure from falling into or making accidental contact with such circuits.
    (4) Grounding. (i) If exposed to contact with electric light and power conductors, the metal sheath of aerial cables entering buildings shall be grounded or shall be interrupted close to the entrance to the building by an insulating joint or equivalent device. Where protective devices are used, they shall be grounded in an approved manner.
    (ii) Masts and metal structures supporting antennas shall be permanently and effectively grounded without splice or connection in the grounding conductor.
    (iii) Transmitters shall be enclosed in a metal frame or grill or separated from the operating space by a barrier, all metallic parts of which are effectively connected to ground. All external metal handles and controls accessible to the operating personnel shall be effectively grounded. Unpowered equipment and enclosures are considered to be grounded where connected to an attached coaxial cable with an effectively grounded metallic shield.
    (f) Solar photovoltaic systems. This paragraph covers solar photovoltaic systems that can be interactive with other electric power production sources or can stand alone with or without electrical energy storage such as batteries. These systems may have ac or dc output for utilization.
    (1) Conductors of different systems. Photovoltaic source circuits and photovoltaic output circuits may not be contained in the same raceway, cable tray, cable, outlet box, junction box, or similar fitting as feeders or branch circuits of other systems, unless the conductors of the different systems are separated by a partition or are connected together.
    (2) Disconnecting means. Means shall be provided to disconnect all current-carrying conductors of a photovoltaic power source from all other conductors in a building or other structure. Where a circuit grounding connection is not designed to be automatically interrupted as part of the ground-fault protection system, a switch or circuit breaker used as disconnecting means may not have a pole in the grounded conductor.
    (g) Integrated electrical systems -- (1) Scope. Paragraph (g) of this section covers integrated electrical systems, other than unit equipment, in which orderly shutdown is necessary to ensure safe operation. An integrated electrical system as used in this section shall be a unitized segment of an industrial wiring system where all of the following conditions are met:
    (i) An orderly shutdown process minimizes employee hazard and equipment damage;
    (ii) The conditions of maintenance and supervision ensure that only qualified persons will service the system; and
    (iii) Effective safeguards are established and maintained.
    (2) Location of overcurrent devices in or on premises. Overcurrent devices that are critical to integrated electrical systems need not be readily accessible to employees as required by §1910.304(f)(1)(iv) if they are located with mounting heights to ensure security from operation by nonqualified persons.
§§1910.309-1910.330   [Reserved]
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Electronic Code of Federal Regulations
e-CFR data is current as of May 24, 2021
Title 29: Labor 
PART 1910 -- OCCUPATIONAL SAFETY AND HEALTH STANDARDS 
Subpart S -- Electrical 

Safety-Related Work Practices
§1910.331   Scope.
    (a) Covered work by both qualified and unqualified persons. The provisions of §§1910.331 through 1910.335 cover electrical safety-related work practices for both qualified persons (those who have training in avoiding the electrical hazards of working on or near exposed energized parts) and unqualified persons (those with little or no such training) working on, near, or with the following installations:
    (1) Premises wiring. Installations of electric conductors and equipment within or on buildings or other structures, and on other premises such as yards, carnival, parking, and other lots, and industrial substations;
    (2) Wiring for connection to supply. Installations of conductors that connect to the supply of electricity; and
    (3) Other wiring. Installations of other outside conductors on the premises.
    (4) Optical fiber cable. Installations of optical fiber cable where such installations are made along with electric conductors.
    Note: See §1910.399 for the definition of "qualified person." See §1910.332 for training requirements that apply to qualified and unqualified persons.
    (b) Other covered work. The provisions of §§1910.331 through 1910.335 also cover:
    (1) Work performed by unqualified persons on, near, or with the installations listed in paragraphs (c)(1) through (4) of this section; and
    (2) Work performed by qualified persons near the installations listed in paragraphs (c)(1) through (c)(4) of this section when that work is not on or directly associated with those installations.
    (c) Excluded work by qualified persons. The provisions of §§1910.331 through 1910.335 do not apply to work performed by qualified persons on or directly associated with the following installations:
    (1) Generation, transmission, and distribution installations. Installations for the generation, control, transformation, transmission, and distribution of electric energy (including communication and metering) located in buildings used for such purposes or located outdoors.
    Note 1 to paragraph (c)(1): Work on or directly associated with installations of utilization equipment used for purposes other than generating, transmitting, or distributing electric energy (such as installations which are in office buildings, warehouses, garages, machine shops, or recreational buildings, or other utilization installations which are not an integral part of a generating installation, substation, or control center) is covered under paragraph (a)(1) of this section.
    Note 2 to paragraph (c)(1): For work on or directly associated with utilization installations, an employer who complies with the work practices of §1910.269 (electric power generation, transmission, and distribution) will be deemed to be in compliance with §§1910.333(c) and 1910.335. However, the requirements of §§1910.332, 1910.333(a), 1910.333(b), and 1910.334 apply to all work on or directly associated with utilization installations, regardless of whether the work is performed by qualified or unqualified persons.
    Note 3 to paragraph (c)(1): Work on or directly associated with generation, transmission, or distribution installations includes:
    (1) Work performed directly on such installations, such as repairing overhead or underground distribution lines or repairing a feed-water pump for the boiler in a generating plant.
    (2) Work directly associated with such installations, such as line-clearance tree trimming and replacing utility poles, when that work is covered by §1910.269 (see §1910.269(a)(1)(i)(D) and (E) and the definition of "line-clearance tree trimming" in §1910.269(x)).
    (3) Work on electric utilization circuits in a generating plant provided that:
    (A) Such circuits are commingled with installations of power generation equipment or circuits, and
    (B) The generation equipment or circuits present greater electrical hazards than those posed by the utilization equipment or circuits (such as exposure to higher voltages or lack of overcurrent protection).
    This work is covered by §1910.269.
    (2) Communications installations. Installations of communication equipment to the extent that the work is covered under §1910.268.
    (3) Installations in vehicles. Installations in ships, watercraft, railway rolling stock, aircraft, or automotive vehicles other than mobile homes and recreational vehicles.
    (4) Railway installations. Installations of railways for generation, transformation, transmission, or distribution of power used exclusively for operation of rolling stock or installations of railways used exclusively for signaling and communication purposes.
[55 FR 32016, Aug. 6, 1990, as amended at 59 FR 4476, Jan. 31, 1994; 79 FR 20692, Apr. 11, 2014; 80 FR 60039, Oct. 5, 2015]
§1910.332   Training.
    (a) Scope. The training requirements contained in this section apply to employees who face a risk of electric shock that is not reduced to a safe level by the electrical installation requirements of §§1910.303 through 1910.308.
    Note: Employees in occupations listed in Table S-4 face such a risk and are required to be trained. Other employees who also may reasonably be expected to face a comparable risk of injury due to electric shock or other electrical hazards must also be trained.
    (b) Content of training -- (1) Practices addressed in this standard. Employees shall be trained in and familiar with the safety-related work practices required by §§1910.331 through 1910.335 that pertain to their respective job assignments.
    (2) Additional requirements for unqualified persons. Employees who are covered by paragraph (a) of this section but who are not qualified persons shall also be trained in and familiar with any electrically related safety practices not specifically addressed by §§1910.331 through 1910.335 but which are necessary for their safety.
    (3) Additional requirements for qualified persons. Qualified persons (i.e., those permitted to work on or near exposed energized parts) shall, at a minimum, be trained in and familiar with the following:
    (i) The skills and techniques necessary to distinguish exposed live parts from other parts of electric equipment,
    (ii) The skills and techniques necessary to determine the nominal voltage of exposed live parts, and
    (iii) The clearance distances specified in §1910.333(c) and the corresponding voltages to which the qualified person will be exposed.
    Note 1: For the purposes of §§1910.331 through 1910.335, a person must have the training required by paragraph (b)(3) of this section in order to be considered a qualified person.
    Note 2: Qualified persons whose work on energized equipment involves either direct contact or contact by means of tools or materials must also have the training needed to meet §1910.333(c)(2).
    (c) Type of training. The training required by this section shall be of the classroom or on-the-job type. The degree of training provided shall be determined by the risk to the employee.
    Table S-4 -- Typical Occupational Categories of Employees Facing a Higher Than Normal Risk of Electrical Accident
                                  Occupation
Blue collar supervisors.[1]
Electrical and electronic engineers.[1]
Electrical and electronic equipment assemblers.[1]
Electrical and electronic technicians.[1]
Electricians.
Industrial machine operators.[1]
Material handling equipment operators.[1]
Mechanics and repairers.[1]
Painters.[1]
Riggers and roustabouts.[1]
Stationary engineers.[1]
Welders.
    1Workers in these groups do not need to be trained if their work or the work of those they supervise does not bring them or the employees they supervise close enough to exposed parts of electric circuits operating at 50 volts or more to ground for a hazard to exist.
[55 FR 32016, Aug. 6, 1990]
§1910.333   Selection and use of work practices.
    (a) General. Safety-related work practices shall be employed to prevent electric shock or other injuries resulting from either direct or indirect electrical contacts, when work is performed near or on equipment or circuits which are or may be energized. The specific safety-related work practices shall be consistent with the nature and extent of the associated electrical hazards.
    (1) Deenergized parts. Live parts to which an employee may be exposed shall be deenergized before the employee works on or near them, unless the employer can demonstrate that deenergizing introduces additional or increased hazards or is infeasible due to equipment design or operational limitations. Live parts that operate at less than 50 volts to ground need not be deenergized if there will be no increased exposure to electrical burns or to explosion due to electric arcs.
    Note 1: Examples of increased or additional hazards include interruption of life support equipment, deactivation of emergency alarm systems, shutdown of hazardous location ventilation equipment, or removal of illumination for an area.
    Note 2: Examples of work that may be performed on or near energized circuit parts because of infeasibility due to equipment design or operational limitations include testing of electric circuits that can only be performed with the circuit energized and work on circuits that form an integral part of a continuous industrial process in a chemical plant that would otherwise need to be completely shut down in order to permit work on one circuit or piece of equipment.
    Note 3: Work on or near deenergized parts is covered by paragraph (b) of this section.
    (2) Energized parts. If the exposed live parts are not deenergized (i.e., for reasons of increased or additional hazards or infeasibility), other safety-related work practices shall be used to protect employees who may be exposed to the electrical hazards involved. Such work practices shall protect employees against contact with energized circuit parts directly with any part of their body or indirectly through some other conductive object. The work practices that are used shall be suitable for the conditions under which the work is to be performed and for the voltage level of the exposed electric conductors or circuit parts. Specific work practice requirements are detailed in paragraph (c) of this section.
    (b) Working on or near exposed deenergized parts -- (1) Application. This paragraph applies to work on exposed deenergized parts or near enough to them to expose the employee to any electrical hazard they present. Conductors and parts of electric equipment that have been deenergized but have not been locked out or tagged in accordance with paragraph (b) of this section shall be treated as energized parts, and paragraph (c) of this section applies to work on or near them.
    (2) Lockout and tagging. While any employee is exposed to contact with parts of fixed electric equipment or circuits which have been deenergized, the circuits energizing the parts shall be locked out or tagged or both in accordance with the requirements of this paragraph. The requirements shall be followed in the order in which they are presented (i.e., paragraph (b)(2)(i) first, then paragraph (b)(2)(ii), etc.).
    Note 1: As used in this section, fixed equipment refers to equipment fastened in place or connected by permanent wiring methods.
    Note 2: Lockout and tagging procedures that comply with paragraphs (c) through (f) of §1910.147 will also be deemed to comply with paragraph (b)(2) of this section provided that:
    (1) The procedures address the electrical safety hazards covered by this Subpart; and
    (2) The procedures also incorporate the requirements of paragraphs (b)(2)(iii)(D) and (b)(2)(iv)(B) of this section.
    (i) Procedures. The employer shall maintain a written copy of the procedures outlined in paragraph (b)(2) and shall make it available for inspection by employees and by the Assistant Secretary of Labor and his or her authorized representatives.
    Note: The written procedures may be in the form of a copy of paragraph (b) of this section.
    (ii) Deenergizing equipment. (A) Safe procedures for deenergizing circuits and equipment shall be determined before circuits or equipment are deenergized.
    (B) The circuits and equipment to be worked on shall be disconnected from all electric energy sources. Control circuit devices, such as push buttons, selector switches, and interlocks, may not be used as the sole means for deenergizing circuits or equipment. Interlocks for electric equipment may not be used as a substitute for lockout and tagging procedures.
    (C) Stored electric energy which might endanger personnel shall be released. Capacitors shall be discharged and high capacitance elements shall be short-circuited and grounded, if the stored electric energy might endanger personnel.
    Note: If the capacitors or associated equipment are handled in meeting this requirement, they shall be treated as energized.
    (D) Stored non-electrical energy in devices that could reenergize electric circuit parts shall be blocked or relieved to the extent that the circuit parts could not be accidentally energized by the device.
    (iii) Application of locks and tags. (A) A lock and a tag shall be placed on each disconnecting means used to deenergize circuits and equipment on which work is to be performed, except as provided in paragraphs (b)(2)(iii)(C) and (b)(2)(iii)(E) of this section. The lock shall be attached so as to prevent persons from operating the disconnecting means unless they resort to undue force or the use of tools.
    (B) Each tag shall contain a statement prohibiting unauthorized operation of the disconnecting means and removal of the tag.
    (C) If a lock cannot be applied, or if the employer can demonstrate that tagging procedures will provide a level of safety equivalent to that obtained by the use of a lock, a tag may be used without a lock.
    (D) A tag used without a lock, as permitted by paragraph (b)(2)(iii)(C) of this section, shall be supplemented by at least one additional safety measure that provides a level of safety equivalent to that obtained by the use of a lock. Examples of additional safety measures include the removal of an isolating circuit element, blocking of a controlling switch, or opening of an extra disconnecting device.
    (E) A lock may be placed without a tag only under the following conditions:
    (1) Only one circuit or piece of equipment is deenergized, and
    (2) The lockout period does not extend beyond the work shift, and
    (3) Employees exposed to the hazards associated with reenergizing the circuit or equipment are familiar with this procedure.
    (iv) Verification of deenergized condition. The requirements of this paragraph shall be met before any circuits or equipment can be considered and worked as deenergized.
    (A) A qualified person shall operate the equipment operating controls or otherwise verify that the equipment cannot be restarted.
    (B) A qualified person shall use test equipment to test the circuit elements and electrical parts of equipment to which employees will be exposed and shall verify that the circuit elements and equipment parts are deenergized. The test shall also determine if any energized condition exists as a result of inadvertently induced voltage or unrelated voltage backfeed even though specific parts of the circuit have been deenergized and presumed to be safe. If the circuit to be tested is over 600 volts, nominal, the test equipment shall be checked for proper operation immediately before and immediately after this test.
    (v) Reenergizing equipment. These requirements shall be met, in the order given, before circuits or equipment are reenergized, even temporarily.
    (A) A qualified person shall conduct tests and visual inspections, as necessary, to verify that all tools, electrical jumpers, shorts, grounds, and other such devices have been removed, so that the circuits and equipment can be safely energized.
    (B) Employees exposed to the hazards associated with reenergizing the circuit or equipment shall be warned to stay clear of circuits and equipment.
    (C) Each lock and tag shall be removed by the employee who applied it or under his or her direct supervision. However, if this employee is absent from the workplace, then the lock or tag may be removed by a qualified person designated to perform this task provided that:
    (1) The employer ensures that the employee who applied the lock or tag is not available at the workplace, and
    (2) The employer ensures that the employee is aware that the lock or tag has been removed before he or she resumes work at that workplace.
    (D) There shall be a visual determination that all employees are clear of the circuits and equipment.
    (c) Working on or near exposed energized parts -- (1) Application. This paragraph applies to work performed on exposed live parts (involving either direct contact or contact by means of tools or materials) or near enough to them for employees to be exposed to any hazard they present.
    (2) Work on energized equipment. Only qualified persons may work on electric circuit parts or equipment that have not been deenergized under the procedures of paragraph (b) of this section. Such persons shall be capable of working safely on energized circuits and shall be familiar with the proper use of special precautionary techniques, personal protective equipment, insulating and shielding materials, and insulated tools.
    (3) Overhead lines. If work is to be performed near overhead lines, the lines shall be deenergized and grounded, or other protective measures shall be provided before work is started. If the lines are to be deenergized, arrangements shall be made with the person or organization that operates or controls the electric circuits involved to deenergize and ground them. If protective measures, such as guarding, isolating, or insulating are provided, these precautions shall prevent employees from contacting such lines directly with any part of their body or indirectly through conductive materials, tools, or equipment.
    Note: The work practices used by qualified persons installing insulating devices on overhead power transmission or distribution lines are covered by §1910.269 of this part, not by §§1910.332 through 1910.335 of this part. Under paragraph (c)(2) of this section, unqualified persons are prohibited from performing this type of work.
    (i) Unqualified persons. (A) When an unqualified person is working in an elevated position near overhead lines, the location shall be such that the person and the longest conductive object he or she may contact cannot come closer to any unguarded, energized overhead line than the following distances:
    (1) For voltages to ground 50kV or below -- 10 ft. (305 cm);
    (2) For voltages to ground over 50kV -- 10 ft. (305 cm) plus 4 in. (10 cm) for every 10kV over 50kV.
    (B) When an unqualified person is working on the ground in the vicinity of overhead lines, the person may not bring any conductive object closer to unguarded, energized overhead lines than the distances given in paragraph (c)(3)(i)(A) of this section.
    Note: For voltages normally encountered with overhead power lines, objects which do not have an insulating rating for the voltage involved are considered to be conductive.
    (ii) Qualified persons. When a qualified person is working in the vicinity of overhead lines, whether in an elevated position or on the ground, the person may not approach or take any conductive object without an approved insulating handle closer to exposed energized parts than shown in Table S-5 unless:
    (A) The person is insulated from the energized part (gloves, with sleeves if necessary, rated for the voltage involved are considered to be insulation of the person from the energized part on which work is performed), or
    (B) The energized part is insulated both from all other conductive objects at a different potential and from the person, or
    (C) The person is insulated from all conductive objects at a potential different from that of the energized part.
    Table S-5 -- Approach Distances for Qualified Employees -- Alternating Current
                        Voltage range (phase to phase)
                           Minimum approach distance
300V and less
Avoid contact.
Over 300V, not over 750V
1 ft. 0 in. (30.5 cm).
Over 750V, not over 2kV
l ft. 6 in. (46 cm).
Over 2kV, not over 15kV
2 ft. 0 in. (61 cm).
Over 15kV, not over 37kV
3 ft. 0 in. (91 cm).
Over 37kV, not over 87.5kV
3 ft. 6 in. (107 cm).
Over 87.5kV, not over 121kV
4 ft. 0 in. (122 cm).
Over 121kV, not over 140kV
4 ft. 6 in. (137 cm).
    (iii) Vehicular and mechanical equipment. (A) Any vehicle or mechanical equipment capable of having parts of its structure elevated near energized overhead lines shall be operated so that a clearance of 10 ft. (305 cm) is maintained. If the voltage is higher than 50kV, the clearance shall be increased 4 in. (10 cm) for every 10kV over that voltage. However, under any of the following conditions, the clearance may be reduced:
    (1) If the vehicle is in transit with its structure lowered, the clearance may be reduced to 4 ft. (122 cm). If the voltage is higher than 50kV, the clearance shall be increased 4 in. (10 cm) for every 10kV over that voltage.
    (2) If insulating barriers are installed to prevent contact with the lines, and if the barriers are rated for the voltage of the line being guarded and are not a part of or an attachment to the vehicle or its raised structure, the clearance may be reduced to a distance within the designed working dimensions of the insulating barrier.
    (3) If the equipment is an aerial lift insulated for the voltage involved, and if the work is performed by a qualified person, the clearance (between the uninsulated portion of the aerial lift and the power line) may be reduced to the distance given in Table S-5.
    (B) Employees standing on the ground may not contact the vehicle or mechanical equipment or any of its attachments, unless:
    (1) The employee is using protective equipment rated for the voltage; or
    (2) The equipment is located so that no uninsulated part of its structure (that portion of the structure that provides a conductive path to employees on the ground) can come closer to the line than permitted in paragraph (c)(3)(iii) of this section.
    (C) If any vehicle or mechanical equipment capable of having parts of its structure elevated near energized overhead lines is intentionally grounded, employees working on the ground near the point of grounding may not stand at the grounding location whenever there is a possibility of overhead line contact. Additional precautions, such as the use of barricades or insulation, shall be taken to protect employees from hazardous ground potentials, depending on earth resistivity and fault currents, which can develop within the first few feet or more outward from the grounding point.
    (4) Illumination. (i) Employees may not enter spaces containing exposed energized parts, unless illumination is provided that enables the employees to perform the work safely.
    (ii) Where lack of illumination or an obstruction precludes observation of the work to be performed, employees may not perform tasks near exposed energized parts. Employees may not reach blindly into areas which may contain energized parts.
    (5) Confined or enclosed work spaces. When an employee works in a confined or enclosed space (such as a manhole or vault) that contains exposed energized parts, the employer shall provide, and the employee shall use, protective shields, protective barriers, or insulating materials as necessary to avoid inadvertent contact with these parts. Doors, hinged panels, and the like shall be secured to prevent their swinging into an employee and causing the employee to contact exposed energized parts.
    (6) Conductive materials and equipment. Conductive materials and equipment that are in contact with any part of an employee's body shall be handled in a manner that will prevent them from contacting exposed energized conductors or circuit parts. If an employee must handle long dimensional conductive objects (such as ducts and pipes) in areas with exposed live parts, the employer shall institute work practices (such as the use of insulation, guarding, and material handling techniques) which will minimize the hazard.
    (7) Portable ladders. Portable ladders shall have nonconductive siderails if they are used where the employee or the ladder could contact exposed energized parts.
    (8) Conductive apparel. Conductive articles of jewelry and clothing (such as watch bands, bracelets, rings, key chains, necklaces, metalized aprons, cloth with conductive thread, or metal headgear) may not be worn if they might contact exposed energized parts. However, such articles may be worn if they are rendered nonconductive by covering, wrapping, or other insulating means.
    (9) Housekeeping duties. Where live parts present an electrical contact hazard, employees may not perform housekeeping duties at such close distances to the parts that there is a possibility of contact, unless adequate safeguards (such as insulating equipment or barriers) are provided. Electrically conductive cleaning materials (including conductive solids such as steel wool, metalized cloth, and silicon carbide, as well as conductive liquid solutions) may not be used in proximity to energized parts unless procedures are followed which will prevent electrical contact.
    (10) Interlocks. Only a qualified person following the requirements of paragraph (c) of this section may defeat an electrical safety interlock, and then only temporarily while he or she is working on the equipment. The interlock system shall be returned to its operable condition when this work is completed.
[55 FR 32016, Aug. 6, 1990; 55 FR 46053, Nov. 1, 1990, as amended at 59 FR 4476, Jan. 31, 1994]
§1910.334   Use of equipment.
    (a) Portable electric equipment. This paragraph applies to the use of cord- and plug-connected equipment, including flexible cord sets (extension cords).
    (1) Handling. Portable equipment shall be handled in a manner which will not cause damage. Flexible electric cords connected to equipment may not be used for raising or lowering the equipment. Flexible cords may not be fastened with staples or otherwise hung in such a fashion as could damage the outer jacket or insulation.
    (2) Visual inspection. (i) Portable cord- and plug-connected equipment and flexible cord sets (extension cords) shall be visually inspected before use on any shift for external defects (such as loose parts, deformed and missing pins, or damage to outer jacket or insulation) and for evidence of possible internal damage (such as pinched or crushed outer jacket). Cord- and plug-connected equipment and flexible cord sets (extension cords) which remain connected once they are put in place and are not exposed to damage need not be visually inspected until they are relocated.
    (ii) If there is a defect or evidence of damage that might expose an employee to injury, the defective or damaged item shall be removed from service, and no employee may use it until repairs and tests necessary to render the equipment safe have been made.
    (iii) When an attachment plug is to be connected to a receptacle (including any on a cord set), the relationship of the plug and receptacle contacts shall first be checked to ensure that they are of proper mating configurations.
    (3) Grounding-type equipment. (i) A flexible cord used with grounding-type equipment shall contain an equipment grounding conductor.
    (ii) Attachment plugs and receptacles may not be connected or altered in a manner which would prevent proper continuity of the equipment grounding conductor at the point where plugs are attached to receptacles. Additionally, these devices may not be altered to allow the grounding pole of a plug to be inserted into slots intended for connection to the current-carrying conductors.
    (iii) Adapters which interrupt the continuity of the equipment grounding connection may not be used.
    (4) Conductive work locations. Portable electric equipment and flexible cords used in highly conductive work locations (such as those inundated with water or other conductive liquids), or in job locations where employees are likely to contact water or conductive liquids, shall be approved for those locations.
    (5) Connecting attachment plugs. (i) Employees' hands may not be wet when plugging and unplugging flexible cords and cord- and plug-connected equipment, if energized equipment is involved.
    (ii) Energized plug and receptacle connections may be handled only with insulating protective equipment if the condition of the connection could provide a conducting path to the employee's hand (if, for example, a cord connector is wet from being immersed in water).
    (iii) Locking-type connectors shall be properly secured after connection.
    (b) Electric power and lighting circuits -- (1) Routine opening and closing of circuits. Load rated switches, circuit breakers, or other devices specifically designed as disconnecting means shall be used for the opening, reversing, or closing of circuits under load conditions. Cable connectors not of the load-break type, fuses, terminal lugs, and cable splice connections may not be used for such purposes, except in an emergency.
    (2) Reclosing circuits after protective device operation. After a circuit is deenergized by a circuit protective device, the circuit may not be manually reenergized until it has been determined that the equipment and circuit can be safely energized. The repetitive manual reclosing of circuit breakers or reenergizing circuits through replaced fuses is prohibited.
    Note: When it can be determined from the design of the circuit and the overcurrent devices involved that the automatic operation of a device was caused by an overload rather than a fault condition, no examination of the circuit or connected equipment is needed before the circuit is reenergized.
    (3) Overcurrent protection modification. Overcurrent protection of circuits and conductors may not be modified, even on a temporary basis, beyond that allowed by §1910.304(e), the installation safety requirements for overcurrent protection.
    (c) Test instruments and equipment -- (1) Use. Only qualified persons may perform testing work on electric circuits or equipment.
    (2) Visual inspection. Test instruments and equipment and all associated test leads, cables, power cords, probes, and connectors shall be visually inspected for external defects and damage before the equipment is used. If there is a defect or evidence of damage that might expose an employee to injury, the defective or damaged item shall be removed from service, and no employee may use it until repairs and tests necessary to render the equipment safe have been made.
    (3) Rating of equipment. Test instruments and equipment and their accessories shall be rated for the circuits and equipment to which they will be connected and shall be designed for the environment in which they will be used.
    (d) Occasional use of flammable or ignitible materials. Where flammable materials are present only occasionally, electric equipment capable of igniting them shall not be used, unless measures are taken to prevent hazardous conditions from developing. Such materials include, but are not limited to: flammable gases, vapors, or liquids; combustible dust; and ignitible fibers or flyings.
    Note: Electrical installation requirements for locations where flammable materials are present on a regular basis are contained in §1910.307.
[55 FR 32019, Aug. 6, 1990]
§1910.335   Safeguards for personnel protection.
    (a) Use of protective equipment -- (1) Personal protective equipment. (i) Employees working in areas where there are potential electrical hazards shall be provided with, and shall use, electrical protective equipment that is appropriate for the specific parts of the body to be protected and for the work to be performed.
    Note: Personal protective equipment requirements are contained in subpart I of this part.
    (ii) Protective equipment shall be maintained in a safe, reliable condition and shall be periodically inspected or tested, as required by §1910.137.
    (iii) If the insulating capability of protective equipment may be subject to damage during use, the insulating material shall be protected. (For example, an outer covering of leather is sometimes used for the protection of rubber insulating material.)
    (iv) Employees shall wear nonconductive head protection wherever there is a danger of head injury from electric shock or burns due to contact with exposed energized parts.
    (v) Employees shall wear protective equipment for the eyes or face wherever there is danger of injury to the eyes or face from electric arcs or flashes or from flying objects resulting from electrical explosion.
    (2) General protective equipment and tools. (i) When working near exposed energized conductors or circuit parts, each employee shall use insulated tools or handling equipment if the tools or handling equipment might make contact with such conductors or parts. If the insulating capability of insulated tools or handling equipment is subject to damage, the insulating material shall be protected.
    (A) Fuse handling equipment, insulated for the circuit voltage, shall be used to remove or install fuses when the fuse terminals are energized.
    (B) Ropes and handlines used near exposed energized parts shall be nonconductive.
    (ii) Protective shields, protective barriers, or insulating materials shall be used to protect each employee from shock, burns, or other electrically related injuries while that employee is working near exposed energized parts which might be accidentally contacted or where dangerous electric heating or arcing might occur. When normally enclosed live parts are exposed for maintenance or repair, they shall be guarded to protect unqualified persons from contact with the live parts.
    (b) Alerting techniques. The following alerting techniques shall be used to warn and protect employees from hazards which could cause injury due to electric shock, burns, or failure of electric equipment parts:
    (1) Safety signs and tags. Safety signs, safety symbols, or accident prevention tags shall be used where necessary to warn employees about electrical hazards which may endanger them, as required by §1910.145.
    (2) Barricades. Barricades shall be used in conjunction with safety signs where it is necessary to prevent or limit employee access to work areas exposing employees to uninsulated energized conductors or circuit parts. Conductive barricades may not be used where they might cause an electrical contact hazard.
    (3) Attendants. If signs and barricades do not provide sufficient warning and protection from electrical hazards, an attendant shall be stationed to warn and protect employees.
[55 FR 32020, Aug. 6, 1990]
§§1910.336-1910.360   [Reserved]
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