EFFECTIVE DATE: 06/20/2011 EXPIRATION DATE: 03/31/2013 

 (Reissue of P10-V-8) 

PROGRAM POLICY LETTER NO. P11-V-16 

FROM: KEVIN G. STRICKLIN 

 Administrator for 

 Coal Mine Safety and Health 

 

 LINDA F. ZEILER 

 Acting Director of Technical Support 

SUBJECT: Suitability, Safety and Performance of Circuit Breakers 

Scope 

This program policy letter (PPL) is intended for Coal Mine Safety and Health 

Administration (MSHA) enforcement and Technical Support audit personnel, 

equipment manufacturers, repair facilities, coal mine operators, independent 

contractors, miners' representatives, and other interested parties. 

Purpose 

This PPL provides guidance on the examination, testing and maintenance requirements 

of circuit breakers under 30 C.F.R. §§ 75.900-3 and 77.900-1 regarding potentially 

dangerous conditions involving circuit breakers, including those that have been 

repaired or rebuilt. It also emphasizes that the mine operator must keep a record of 

such examinations. 

Policy 

Under 30 C.F.R. §§ 75.900-3 and 77.900-1, circuit breakers, including those that have 

been repaired or rebuilt, must be examined and tested monthly and properly 

maintained by a qualified person to assure that they are in safe operating condition. In 

addition, under § 75.512 and 77.502, during the weekly and monthly examination of 

electric equipment, when a potentially dangerous condition is found related to a circuit 
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breaker, the circuit breaker must be removed from service until such condition is 

corrected. 

Some characteristics that should be addressed during the examination or maintenance 

of circuit breakers, including those that have been repaired or rebuilt include: 

integrityand strength of the housing; internal and external electrical insulation; all 

component parts must be present and in working condition; identification labeling; and 

cleanliness. 

In addition, 30 C.F.R. §§ 75.900-4 and 77.900-2 require that a record of examinations, 

testing, repairs, and adjustments be kept in a secure book approved by the Secretary. 

When a circuit breaker is sent to a repair/rebuild facility for repairs and/or 

adjustments, a report of all repairs and adjustments should accompany the circuit 

breaker and the report should be included in the record book. 

The attachment “Recommended Guidelines on Repair or Rebuild and Maintenance of 

Circuit Breakers” provides guidance for inspectors, auditors, mine operators, repair and 

rebuild shops, contractors, miners’ representatives, and other interested parties in 

recognizing improperly repaired or rebuilt or inadequately maintained circuit breakers. 

Background 

MSHA has become aware of issues relative to circuit breakers that have not been 

adequately maintained or have been improperly repaired or rebuilt. These issues have 

been the cause of numerous serious accidents and at least one fatality. Some of the 

hazardous conditions caused by inadequately maintained or improperly repaired or 

rebuilt circuit breakers include: 

 Circuit breakers are incorrectly labeled. The worst case is circuit breakers labeled 

for use at 1000 Volts, when in fact the circuit breaker was only rated for 600 

Volts. This situation could cause the circuit breaker to flash across the phases, 

causing an arc blast, which could cause injury to any personnel close to the 

circuit breaker.

 Cases and components have been found shot blasted as part of the cleaning 

process. Shot blasting decreases the insulating characteristics of the case and 

may compromise the physical integrity of the case.

 Painted circuit breakers have been found in use in the mine. This decreases its 

insulating characteristics and can become a component of a plasma ball in the 

event of a catastrophic internal event, such as an arc blast. Painting the 

components inside of a circuit breaker, such as the arc chutes, have kept the 

component from performing its function, which allows internal damage to occur 

during normal operation.

 Damaged and modified cases have been found repaired with epoxy. Epoxy or 

other repair materials used for case repair do not have the strength or insulating 
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characteristics of the original material. In the event a circuit breaker has to clear 

a bolted fault, these areas could give way and allow pieces of the case to become 

shrapnel. A case that is cracked or is missing pieces should be destroyed and 

discarded.
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 Circuit breaker cases have been found with significant overheating signs. 

Overheating is an indication that something abnormal is occurring inside the 

case. This could be the result of a loose connection or a failing contact tip and 

could lead to a catastrophic failure of the circuit breaker.

 Trip unit settings have been found to be set too high. This can cause damage to 

the cable being protected, as well as posing a risk of electrical shock and fire.

 Metallic fixtures have been found attached to a circuit breaker. Anything 

metallic that has not been designed to be attached to a circuit breaker can become 

energized and pose an electrical shock hazard.

 Internal modifications to the case have been found. An internal modification to 

the case can weaken its structural integrity. Specifically, modifying the ribs 

between the phases can cause an internal phase to phase short circuit to occur. 

Removing material from the sides of the case can prevent the case from 

containing a fault event and may leave an opening that can pose a shock hazard.

 Circuit breakers have been found with missing and broken components. Each 

component inside a circuit breaker has a designed purpose. Certain components 

prevent electrical shock; other components dampen the arc of a circuit breaker 

operating under load, or provide insulation that prevents an internal short 

circuit.

 Replaced contact tips have been found that were not designed to work in a 

circuit breaker. The hazard in using contact tips not designed for a circuit 

breaker is that the tips can weld closed and affect the function of the breaker. 

This condition was the cause of a fatality.

 Undervoltage relays (UVR) that were not designed to fit in the circuit breaker 

have been found. To install an incorrect UVR, a case modification that can 

compromise its integrity may have to be made. The use of an incorrect UVR may 

compromise its function and the function of the breaker. 

 UVRs have been adjusted or blocked to prevent the circuit breaker from tripping. 

If the UVR cannot perform its function, critical faults will not be cleared. This 

will cause a dangerous condition that can result in a serious injury or a fatality. 

MSHA’s authority for this PPL

The Federal Mine Safety and Health Act of 1977, as amended, 30 U.S.C. § 801 et seq.; 30 

§§ C.F.R. 75.512, 77.502, 75.900-3, and 77.900-1. 

Filing Instructions

This PPL should be filed behind the tab marked "Program Policy Letters" at the back of 

Volume II in the Program Policy Manual.

Internet Availability 

This PPL may be viewed on the Internet by accessing the MSHA Home Page at 

(http://www.msha.gov) choosing “Compliance Info,” then choosing “Program Policy 

Letters.” 
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Issuing Office and Contact Person 

Coal Mine Safety and Health, Safety Division 

Charles Carpenter, (202) 693-9532 

E-mail: carpenter.charles@dol.gov 

Technical Support, Approval and Certification Center 

Richard O’Hanlon, (304) 547-2071 

E-mail: ohanlon.richard@dol.gov

Distribution

MSHA Program Policy Manual Holders 

MSHA Special Interest Groups 

Coal Mine Operators 

Attachment 
RECOMMENDED GUIDELINES on REPAIR or REBUILD and MAINTENANCE of

CIRCUIT BREAKERS

 (NOTE: Pictures used are only examples.) 

Prior History of Rebuild/Repair Facility

Based on inspection history and complaints, has the vendor had any previous issues 

with repair/rebuild problems that have required the removal and/or repair of a 

breaker repaired/rebuilt by that vendor? 

External Criteria for further inspection and/or removal from service

1. Labeling – if visible 

a. If the circuit breaker has been rebuilt by a third party facility, it should 

have the name of that rebuild facility attached. 

b. A new or OEM rebuilt breaker should have OEM labeling. Most OEM 

labeling can be identified by a label number. Comparison will show lack 

of a number; different font sizes; layouts not the same; and possible 

misspellings. OEM labels that have been reproduced may be an 

indication of problems. See pictures below. 

 OEM NON-OEM 

c. Circuit breaker full load current, voltage, and type should be present. 

2. Shot Blasting 

Shot blasting removes resin from the case and may weaken the 

structure so that it could fail under a catastrophic event inside the 

breaker, such as an arc blast. This is an indicator for further 

inspection.
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Shot Blasted & Painted 

3. Paint 

Paint on the outside of the case does not pose a hazard. However, 

painting could mask other hazards. Therefore, paint on the exterior of a 

circuit breaker case is cause to have the mine operator open the circuit 

breaker for a more in depth inspection. 

4. Epoxy Repairs 

Cases repaired and/or modified using epoxy can be hazardous. A 

damaged case can be weak enough that an event occurring inside the 

circuit breaker can cause the case to fail and rupture causing the epoxy to 

become shrapnel that can injure personnel nearby. The patching material 

may not be enough to restore the case’s strength. Some patching material 

may be conductive and can cause a shock hazard. 

Epoxy Repair to Case Corner Epoxy Modification to Cover 
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5. Hairline Cracks, Broken Pieces 

Hairline cracks and broken pieces on the case can present a serious hazard 

in that they compromise the integrity of the case in the event of a fault. 

Cracks in the case also compromise the electrical integrity of the circuit 

breaker and can pose a risk of arcing. 

Cracked Case 

6. Signs of Overheating 

Signs of overheating (such as carbon smears, warped or melted case, 

and/or burnt areas) are cause for having the mine operator open a circuit 

breaker for a more in depth inspection or removal from service. These are 

indicators that the circuit breaker case integrity has been compromised. 

Signs of overheating are also indicators that the electrical insulation 

between the phases may have been compromised through carbon 

tracking. 

Bubbled & Charred 
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7. Trip Unit Settings 

If the circuit breaker trip unit is not properly set, it can cause damage to 

the cable it is protecting. It also poses the hazards of shock and fire. The 

trip unit must be visibly identified to ensure it is adjusted correctly. 

Settings on High 

8. Metallic Fixtures Attached to the Breaker Cover or Housing 

Circuit breakers should not have anything attached to the case, and 

especially not with metallic fasteners. However, some of the older circuit 

breakers still in use have metallic ID tags fastened to the outside of the 

breaker with metal rivets. The metallic plate is an indicator to inspect for 

insulating material inside the breaker. These rivets must not extend to the 

inside of the case. If the rivet hole is drilled through, it must be insulated 

with a suitable dielectric. Failure to follow this requirement could allow a 

dangerous electric potential to be present on the exterior of the breaker, 

which could be contacted by personnel. 

Metallic Tag (Painted) 
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Internal Criteria for further inspection and/or removal from service

1. Modifications 

A modification is anything that changes the structure of the case. The 

Original Equipment Manufacturer (OEM) provides acceptable 

modification instructions for permitted accessory installation. Any other 

modification will be considered criteria for removal from service. Some 

instances of non-specified or unapproved modifications are: 

 holes through the outside of the case, except as allowed by the 

OEM. Example: a hole for wire from an auxiliary switch to pass 

through from the inside of the case that is no longer used would be 

allowed 

 cut-outs between the phases that compromise the electrical 

separation 

 cut-outs that are not as specified by the OEM for mounting a UVR 

or other certified component 

These types of modifications cause hazards that would allow: 

 the potential for shock due to exposure of a miner to fault current 

 arcing between phases 

 case failure during an electrical fault 

 Tape Around Movable Arm Case Phase Barrier Cut Away 
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2. Paint 

Paint inside the case of a circuit breaker creates at least two hazardous 

conditions. The first is a change in insulation characteristics of the molded 

case. Over time, the paint can deteriorate from the heat and ionization 

that occurs in the circuit breaker. This can lead to carbon tracking 

between the phases and subsequent phase to phase and/or phase to 

ground faults. The second hazard is the addition of a potentially 

flammable component to a plasma ball occurring because of a fault. Be 

aware, some Westinghouse 1000 volt circuit breakers do have a dielectric 

coating that resembles paint inside the breaker case and cover. 

Painted & Shot Blasted 

3. Shot Blasting 

As noted above, any shot blasting may weaken the case integrity, but 

internal shot blasting also changes the insulating characteristics of the 

case, which can lead to arcing between the phases. This can happen when 

the exposed fibers catch conductive material that builds up and eventually 

leads to a track between phases. 

4. Missing and/or Broken Parts 

There are removable insulators (fish boards) within the circuit breaker 

case. If any of the fish boards, (cardboard like tabs around the tips), 

inserts along side of the reset handle that allow removal of the reset 

mechanism, or any of the top and/or bottom phase insulators are missing 

or broken, a short circuit hazard or electrical shock hazard is created. 

Missing components, such as missing or damaged arc chutes, can pose an 

arc flash hazard. 
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 Fish Boards Broken Trip Unit Housing 

5. Contact Tips 

Contact tips used in mining circuit breakers are made of a special alloy 

that allows the tips to open under load without welding. The use of tips 

other than those specified by the circuit breaker manufacturer pose a risk 

of welding under load. The hazard is potentially life threatening and has 

caused the death of at least one miner and serious injuries to others. 

Welded Contact Tips 

6. Painted or Damaged Arc Chutes 

The arc chutes in a circuit breaker are designed to spread and cool the arc 

that occurs when the tips break. Paint covering the arc chute diminishes 

or prevents the arc from being extinguished in a controlled manner. In 

addition, the paint can contribute to the arc’s heat and plasma ball. A 

damaged arc chute can also minimize the effect the arc chute has on 

extinguishing the arc. An uncontrolled arc can lead to a short circuit event 

inside the circuit breaker causing an arc explosion. 
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Painted Arc Chute 

7. Insulation Between Phases 

The circuit breaker case is designed to maintain the arc flash, caused by a 

breaker opening under load, inside the case and to prevent any shorting 

between the phases. The material of the case between the phases can be 

compromised through damage, such as cracks or broken pieces, or from 

modifications not approved by the manufacturer of the circuit breaker. 

This can cause the case to become weakened enough that it will no longer 

contain the force it was designed to contain and/or the electrical clearance 

between the phases could be compromised and allow an arcing short to 

occur. Either can cause injury to personnel in proximity to the breaker. 

Cover Insulation Cut Away 

8. UVR Undamaged and Adjusted Properly 

The ground fault, ground wire monitor, and undervoltage protection 

circuits rely on the undervoltage release relay (UVR). If the relay is 

damaged or not properly adjusted, these safety circuits cannot operate the 

breaker. An inoperative UVR poses hazards of injury, fire, and death. 
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Trip Unit Visibly Identified 

The trip unit must be visibly identified in order to ensure it is adjusted 

properly to protect the cable attached to the output connector. The 

identifier must be clearly visible and it must agree with the markings on 

the trip unit, if it is placed on the outside of breaker case. A trip unit that 

has had the identification markings removed or the wrong identification 

attached through human error could allow the cable it is protecting to 

experience enough current on a fault to generate enough heat to cause a 

fire. 

Trip Unit ID and Settings 

UVR Adjustment Points 

Trip Unit 

Range in 

Agreement 

Undervoltage 

trip range 

adjustment 

Trip adjustment 
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9. 1000V - Swab Test Pass (Westinghouse Only) 

Classic 1000 VAC Westinghouse (now Eaton/Cutler-Hammer) circuit 

breaker frames HMAM, HLAM and HKAM that are new or refurbished 

by the OEM can be verified as rated for 1000 VAC by performing a “swab 

test” of the inside of the circuit breaker. A 1000 VAC rated circuit breaker 

is coated with a special insulator/anti-track paint that is necessary for the 

safety of the circuit breaker. A cloth or cotton tipped swab that has 

solvent applied to it and is wiped across the inside frame of the breaker at 

the arc chute area of the case will have blue tint from this coating. The 

inside of the cover at the arc chute area also has this coating applied. The 

cloth or cotton tipped swab with solvent applied to it will cause a minute 

amount of the coating to adhere to it, causing the blue color. If a new or 

OEM refurbished Westinghouse 1000 VAC breaker of these types does not 

return a blue color after being “swab tested”, it may not be able to handle 

the energy generated during a fault. 

Operation

1. Trips on Operation of Safety Circuit 

The circuit breaker must trip on overcurrent, grounded phase, short 

circuit, undervoltage, and loss of ground wire monitor. The circuit 

breaker must be tested for trip functionality at least monthly. The easiest 

and most generally used safety circuit to test the trip functionality is the 

ground-wire monitor circuit. It is recommended that the other safety 

circuits be occasionally utilized for testing tripping operation in order to 

ensure full functionality of the safety devices.