ISSUE DATE: 11/28/2011

PROGRAM INFORMATION BULLETIN NO. P11-51

FROM: LINDA F. ZEILER

Director of Technical Support 

KEVIN G. STRICKLIN

Administrator for

Coal Mine Safety and Health

SUBJECT: De-energizing a Non-intrinsically Safe Automatic Fire Sensor

and Warning Systems after a Main Mine Fan Stoppage

Scope

This Program Information Bulletin (PIB) applies to underground mine operators, 

miners’ representatives, mining equipment manufacturers, Mine Safety and Health 

Administration (MSHA) enforcement personnel and other interested parties.

Purpose

The purpose of this PIB is to remind the mining community that a non-intrinsically safe 

automatic fire sensor and warning device system, whether or not connected to an 

Atmospheric Monitoring System (AMS), must be de-energized after a main mine fan 

stoppage.

Information

Title 30, Code of Regulations (C.F.R.) § 75.313(c)(2) requires that underground 

electrically powered equipment be de-energized if ventilation is not restored within 15 

minutes after a main mine fan stoppage. A non-intrinsically safe automatic fire sensor 

and warning device system, whether or not it is connected to an AMS is considered 

electrically powered equipment and must be de-energized after a main mine fan 

stoppage.

30 C.F.R. § 75.1103-4(e) requires that, except when power must be cut off in the mine

under the provisions of § 75.313, automatic fire sensor and warning device systems 

shall be capable of giving warning of fire for a minimum of 4 hours after the electrical
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power is cut off. This battery backup is not permitted after a main mine fan stoppage 

unless the system is intrinsically safe, thus the batteries must be disconnected.

In order to comply with §§ 75.313 and 75.1103-7, a system with battery backup power

that cannot be disconnected remotely from the surface must be intrinsically safe or have 

a relay to automatically disconnect the battery power supply. A manually operated 

switch actuated by a miner leaving the section is not acceptable to de-energize 

individual batteries (MSHA Handbook Number PH-08-V-2, page 10, item 3).

After the entire area monitored by the automatic fire sensor and warning device system 

or AMS is examined, power can be restored to the system and the batteries reconnected. 

Depending on the system installed, a manual reconnect of the batteries may be needed 

at each individual unit.

Background

MSHA became aware of an incident where a non-intrinsically safe Pyott-Boone CO 

Monitoring System was energized by battery power for several hours after a main mine 

fan stoppage. During the period of the mine fan stoppage, mine personnel were 

exposed to dangerous conditions by having energized non-intrinsically safe equipment 

in a potentially explosive atmosphere.

MSHA's authority for this PIB

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

C.F.R. §§ 75.313, 75.1103-4(e), 75.1103-5(c) and 75.1103-7.

Internet Availability

This information bulletin may be viewed on the Internet by accessing MSHA's home 

page at (http://www.MSHA.gov) and then choosing Compliance Info and Program 

Information Bulletins.

MSHA contact persons for this bulletin

Technical Support, Approval and Certification Center

Kenneth Sproul, (304) 547-2038

E-mail: sproul.kenneth@dol.gov

Coal Mine Safety and Health, Safety Division

John Arrington, (202) 693-9549

E-mail: arrington.john@dol.gov
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Distribution

Underground Mine Operators

Mining Equipment Manufacturers

Miners’ Representatives