DEPARTMENT OF HEALTH AND HUMAN SERVICES

Centers for Disease Control and Prevention

National Institute for Occupational Safety and Health

Summary

Workers are at risk of severe 

injury and death during machine maintenance and servicing if proper lockout and tagout 

procedures are not followed. 

NIOSH recommends developing and implementing a hazardous energy control program 

including lockout and tagout 

procedures and worker training 

to prevent such incidents. 

Using Lockout and Tagout Procedures 

to Prevent Injury and Death during 

Machine Maintenance

Description of 

Exposure

Machine-related injuries or fatalities 

can occur during maintenance and 

servicing tasks when workers are exposed to an uncontrolled release of 

energy or during unexpected equipment startup. During 1982–2006, 

NIOSH investigated 185 fatalities related to installation, maintenance, 

service, or repair tasks on or near 

machines, equipment, processes, or 

systems. Investigations were carried 

out in 20 States as part of the Fatality Assessment and Control Evaluation (FACE) Program. Failure to 

completely de-energize, block, and/

or dissipate the energy source was a 

factor in 142 (77%) of the incidents; 

failure to lockout and tagout energy 

control devices and isolation points 

after de-energization was a factor in 

31 (17%). If machines start up during maintenance, repair, adjusting, 

or servicing, workers can be caught 

in the machinery and suffer fractures, crushing injuries, amputations, or death [NIOSH 1999, 2006]. 

Application of the 

Lockout/Tagout 

Standard

Incidents related to lockout/tagout 

procedures were the most cited violation in manufacturing by the Occupational Safety and Health Administration (OSHA) during 2006–2007 

[Jarrell and Washam 2009]. One study 

analyzed OSHA accident investigation 

reports from 1984−1997 and found 

that in more than half of the 348 investigated cases, lockout procedures were 

“not even attempted” [Bulzacchelli et 

al. 2008]. These figures reinforce the 

necessity of having a written hazardous 

energy control program and ensuring 

that employees understand and follow 

the procedures.

Lockout/tagout procedures APPLY 

in the following circumstances:

 Workers are servicing and maintaining equipment, and unexpected startup of the machine or release of stored energy could occur 

[Jarrell and Washam 2009]

 When, during normal production, 

workers must remove or bypass a 

guard or safety device [Jarrell and 

Washam 2009]

 When, during normal production, 

workers place any part of their body 

into the danger zone or near the 

machine’s point of operation [OSHA 

2002]

 During all set up activities [Jarrell 

and Washam 2009]
The millwright had been trained in general lockout/tagout procedures on the job, but the procedures failed to 

address the following: 

 The use of locks to ensure that the electrical sources 

remain disconnected

 The disconnect locations for the six electrical energy sources and one pneumatic energy source for the debarker

 Procedures for bleeding, blocking, and verifying that 

stored pneumatic energy (air pressure) had been rendered safe 

 Clearly labeling each lock with a durable tag (or durable label or marking) to identify the worker assigned to 

a lock that is used to secure an energy control device

Recommendations

NIOSH recommends that employers and workers take 

the following steps to prevent machine-related injuries: 

Employers

NIOSH recommends that employers comply with the 

OSHA regulations outlined in 29 CFR* 1910.147, the 

control of hazardous energy (lockout/tagout). Results 

of NIOSH fatality investigations indicate that the following steps are particularly important.

 Develop and implement a written hazardous energy control program, including lockout/tagout procedures, employee training, and inspections before any 

maintenance or service work is done [NIOSH 1999].

 Be sure that workers have a clear understanding of 

when hazardous energy control procedures apply and 

training on how to properly apply the procedures.

 Ensure that procedures on lockout/tagout are developed that are specific to each machine [NIOSH 2006; 

Michalscheck 2008].

 Provide training to production workers in addition to 

maintenance workers in methods of energy isolation 

and control [see 29 CFR 1910.147(b)]. 

 To effectively isolate each energy source, ensure that 

workers are provided with a sufficient number of 

lockouts and tagouts and other hardware that may be 

needed [See 29 CFR 1910.147(c)(5)(i)].

 Clearly label isolation devices, such as breaker panels 

and control valves [NIOSH 1999].

 After removing the lockout or tagout devices but before 

starting the machine, be sure that all employees who 

* Code of Federal Regulations. See CFR in References.

Case Report

The NIOSH FACE program investigated the following 

incident in which a millwright was fatally injured because of an uncontrolled release of energy while he was 

repairing a debarker [NIOSH 2006]:

The teeth on the debarker feed rolls had become worn, 

and the worker had been assigned to weld additional 

metal to build up the feed roll teeth. He had not conducted this type of repair before. 

To safely de-energize this machine, six electrical sources and one pneumatic energy source needed to be disconnected and locked out, and the pressure in the air 

line that automatically controls the up and down motion of the feed rolls needed to be bled off. The victim 

disconnected and locked out two of the electrical sources (See Figure 1), but he did not disconnect and lock 

out the other four electrical sources or the pneumatic 

energy source, and he did not bleed off the pressure in 

the air lines. In this condition, the machine’s automatic 

control system remained energized. As the victim welded metal to the feed roll teeth, he leaned forward and 

placed his head between the feed rolls to reach areas 

that required more metal. The feed rolls automatically 

cycled, and closed over his head. 

His supervisor had left to check on another machine 

and when he returned, he found the millwright caught 

in the machine. Emergency medical services personnel 

arrived 20 minutes after receiving the 911 call and 

attempted cardiopulmonary resuscitation, but the millwright had died. 

Figure 1. This photo illustrates the south debarker room 

where locks had been placed on two electrical circuits by 

the victim [Photo courtesy of SCOSHA].
operate or work with the machine, as well as those in 

the area where service or maintenance is performed, 

know that the devices have been removed and that the 

machine is capable of being re-energized [OSHA 2002; 

29 CFR Part 1910.147 (e)(3)]. 

 Ensure that no one under the age of 18 works on machinery declared hazardous in the Child Labor Rules 

[29 CFR 570.120].

 Ensure that workers receive training in their primary language.

Workers

 Follow the regulations contained in your employer’s 

hazardous energy control program.

 Complete all employer-provided training on hazardous energy control procedures.

 Before beginning machine adjustment, maintenance, 

or servicing work, do the following [NIOSH 1999]: 

1. De-energize all sources of hazardous energy:

— Disconnect or shut down engines or motors.

— De-energize electrical circuits.

— Block fluid (gas or liquid) flow in hydraulic 

or pneumatic systems.

— Block machine parts against motion. 

2. Lockout and tagout all forms of hazardous energy, including electrical breaker panels and control valves.†

3. Block or dissipate stored energy:

— Discharge capacitors.

— Release or block springs that are under compression or tension.

— Vent fluids from pressure vessels, tanks, or 

accumulators, but never vent toxic, flammable, or explosive substances directly into the 

atmosphere. 

 Make sure that only one key exists for each of your assigned locks and that only you hold that key.‡

 

 Verify by test and/or observation that all energy 

sources are de-energized. 

† OSHA standards require the use of either lockout or tagout. However, 

NIOSH [1999] recommends that any hazardous control program include 

both to ensure maximum protection. Also note that some State plans may 

have more stringent requirements than those found in 29 CFR 1910.147.

‡ Use of master keys should be reserved for unusual circumstances when the 

worker is absent from the workplace. However, if master keys are necessary, 

keep them under supervisory control. List the proper procedures for using 

them in the written program for controlling hazardous energy.

 Inspect repair work before removing your lock and 

activating the equipment. 

 Make sure that only you remove your assigned lock. 

 Make sure that you and your coworkers are clear of 

danger points before re-energizing the system (see 29 

CFR 1910.147(e) and 29 CFR 1910.117(f). 

Manufacturers

Consider designing equipment that requires fewer and 

more easily accessible disconnect points to facilitate the 

use of safe lockout/tagout procedures for maintenance 

and repair [NIOSH 2006].

OSHA Information

For information about energy control procedures, protective equipment, inspection, and training, see (http://www.

osha.gov/pls/oshaweb/owadisp.show_document?p_

table=STANDARDS&p_id=9804). OSHA has a Lockout-Tagout Interactive Training Program that can be 

useful in better understanding the requirements of the 

OSHA hazardous energy control standard (http://www.

osha.gov/dts/osta/lototraining/index.html ).

Acknowledgments

This document was developed by Susan Afanuh, Education and Information Division (NIOSH); and Paul Moore 

and Tim Pizatella, Division of Safety Research (NIOSH).

References

Bulzacchelli MT, Vernick JS, Sorock GS, Webster, DW, Lees 

PSJ [2008]. Circumstances of fatal lockout/tagout-related 

injuries in manufacturing. Am J Ind Med 51:728–734.

CFR. Code of Federal regulations. Washington, DC: U.S. 

Government Printing Office, Office of the Federal Register.

Jarrell JL, Washam J [2009]. Lockout/tagout: controlling hazardous energy to prevent workplace injury. Washington, 

DC: OSHA Training and Education Directorate, OSHA 

Course No. 7115.

Michalscheck J [2008]. Lockout/tagout: are the hazards misunderstood? EHS Today Dec: 38–43. http://ehstoday.com/safety/best-practices/lockouttagout_hazards_misunderstood/ 

NIOSH [1999]. NIOSH Alert: preventing worker deaths from 

uncontrolled release of electrical, mechanical, and other 

types of hazardous energy. Cincinnati, OH: U.S. Department 

of Health and Human Services, Centers for Disease Control 

and Prevention, National Institute for Occupational Safety and Health, DHHS (NIOSH) Publication No. 99−110. 

http://www.cdc.gov/niosh/docs/99-110/
DEPARTMENT OF HEALTH AND HUMAN SERVICES

Centers for Disease Control and Prevention

National Institute for Occupational Safety and Health

4676 Columbia Parkway

Cincinnati, OH 45226–1998

Official Business

Penalty for Private Use $300

The information in this document is based on field research and 

FACE reports. More information about the FACE program is available at http://www.cdc.gov/niosh/face/.

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Mention of any company or product does not constitute endorsement by NIOSH. In addition, citations to Web sites external to NIOSH do not constitute NIOSH endorsement of the 

sponsoring organizations or their programs or products. Furthermore, NIOSH is not responsible for the content of these Web sites. 

This document is in the public domain and may be freely 

copied or reprinted. NIOSH encourages all readers of the 

Workplace Solutions to make them available to all interested employers and workers.

As part of the Centers for Disease Control and Prevention, NIOSH 

is the Federal agency responsible for conducting research and 

making recommendations to prevent work-related illnesses and 

injuries. All Workplace Solutions are based on research studies that 

show how worker exposures to hazardous agents or activities can 

be significantly reduced. 

Using Lockout and Tagout Procedures to Prevent 

Injury and Death during Machine Maintenance

DHHS (NIOSH) Publication No. 2011–156

Safer • Healthier • PeopleTM April 2011

For More Information

NIOSH [2006]. Millwright killed when pinned between the 

feed rolls of a debarker during machine maintenance—

South Carolina. Morgantown, WV: U.S. Department of 

Health and Human Services, Centers for Disease Control 

and Prevention, National Institute for Occupational Safety 

and Health, DHHS (NIOSH) FACE Report 2006−02. http://

www.cdc.gov/niosh/face/In-house/full200602.html 

OSHA [2002]. Control of hazardous energy: lockout/tagout 

(2002 Revised). Washington, DC: U.S. Department of Labor, 

Occupational Safety and Health Administration.