[Code of Federal Regulations]
[Title 30, Volume 1]
[Revised as of July 1, 2002]
From the U.S. Government Printing Office via GPO Access
[CITE: 30CFR27.34]

[Page 146]
 
                       TITLE 30--MINERAL RESOURCES
 
  CHAPTER I--MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR
 
PART 27--METHANE-MONITORING SYSTEMS--Table of Contents
 
                      Subpart C--Test Requirements
 
Sec. 27.34  Test for intrinsic safety.

    Assemblies, subassemblies, or components that are designed for 
intrinsic safety shall be tested by introducing into the circuit(s) 
thereof a circuit-interrupting device which produces an electric spark 
from the current in the circuit. The circuit-interrupting device shall 
be placed in a gallery containing various flammable natural gas-air 
mixtures. To meet the requirements of this test, the spark shall not 
ignite the flammable mixture. For this test the circuit-interrupting 
device shall be operated not less than 100 times at 125 percent of the 
normal operating voltage of the particular circuit.