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U.S. Department of Labor

Mine Safety and Health Administration
201 12th Street South, Suite 401
Arlington, VA 22202-5450

EFFECTIVE DATE:   May 22, 2012 EXPIRATION DATE: 3/31/2024      
LAST VALIDATED: 03/31/2021


                     Administrator for
                     Coal Mine Safety and Health

SUBJECT:     Circuit Identification under 30 C.F.R. § 75.903 and 75.904

This Program Policy Letter (PPL) applies to coal mine operators, Coal Mine Safety and Health Administration (MSHA) enforcement personnel and other interested parties.

The purpose of this PPL is to clarify how electrical circuits should be identified under 30 C.F.R. § 75.903 to provide visual evidence that the power to equipment is disconnected to ensure safe operation and maintenance of the equipment.

Section 75.903, Disconnecting Devices, requires that a disconnecting device be installed in conjunction with the circuit breaker to provide visual evidence that the power is disconnected.

Section § 75.904 requires circuit breakers to be marked for identification.  Additionally, § 75.601 requires disconnecting devices used to disconnect power from trailing cables to be plainly marked and identified and designed in a manner to be able to determine by visual observation that the power is disconnected.

A "disconnecting device" includes both a trailing cable plug (cathead) and the receptacle into which it is plugged.  To provide visual evidence that the power is disconnected between the circuit breaker and disconnecting device, all three components -- the circuit breaker, the receptacle, and the trailing cable plug -- must be labeled in a similar manner.  For example, the trailing cable plug, receptacle and circuit breaker serving loading machine #1 should each be labeled "Loader #1."  Labeling disconnecting devices and circuit breakers in a similar manner, for example, with the name of the equipment being energized, will reduce the chance of energizing the circuit while repairs are being made to the equipment.

MSHA has received questions on labeling requirements involving circuit breakers, trailing cable plugs, and receptacles.  There have been several accidents involving repairs to electric equipment and inadequate labeling of circuits.

The Federal Mine Safety and Health Act of 1977, as amended, 30 U.S.C. § 801 et seq., and 30 C.F.R. §§ 75.601, 75.903, and 75.904.

Internet Availability
This PPL may be viewed on the Internet by accessing MSHA home page ( and then choosing“Compliance Info” and “Program Policy Letters.” 

Issuing Office and Contact Persons**
Mine Safety and Health Enforcement, Safety Division
Rodney Adamson, (202) 693-9549

MSHA Program Policy Manual Holders
Special Interest Groups
Coal Mine Operators