[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: 30CFR27.20]

[Page 143-144]
 
                       TITLE 30--MINERAL RESOURCES
 
  CHAPTER I--MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR
 
PART 27--METHANE-MONITORING SYSTEMS--Table of Contents
 
             Subpart B--Construction and Design Requirements
 
Sec. 27.20  Quality of material, workmanship, and design.


    (a) MSHA will test only equipment that, in its opinion, is 
constructed of suitable materials, is of good workmanship, is based on 
sound engineering principles, and is safe for its intended use. Since 
all possible designs, arrangements, or combinations of components cannot 
be foreseen, MSHA reserves the right to modify the construction and 
design requirements of components or subassemblies and the tests to 
obtain the degree of protection intended by the tests described in 
Subpart C of this part.
    (b) Unless otherwise noted, the requirements stated in this part 
shall apply to explosion-proof enclosures and intrinsically safe 
circuits.
    (c) All components, subassemblies, and assemblies shall be designed 
and

[[Page 144]]

constructed in a manner that will not create an explosion or fire 
hazard.
    (d) All assemblies or enclosures--explosion-proof or intrinsically 
safe--shall be so designed that the temperatures of the external 
surfaces, during continuous operation, do not exceed 150  deg.C. (302 
deg.F.) at any point.
    (e) Lenses or globes shall be protected against damage by guards or 
by location.
    (f) If MSHA determines that an explosion hazard can be created by 
breakage of a bulb having an incandescent filament, the bulb mounting 
shall be so constructed that the bulb will be ejected if the bulb glass 
enclosing the filament is broken.
    Note: Other methods that provide equivalent protection against 
explosion hazards from incandescent filaments may be considered 
satisfactory at the discretion of MSHA.