[Code of Federal Regulations]

[Title 30, Volume 1]

[Revised as of July 1, 2006]

From the U.S. Government Printing Office via GPO Access

[CITE: 30CFR18.38]



[Page 106-107]

 

                       TITLE 30--MINERAL RESOURCES

 

  CHAPTER I--MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR

 

PART 18_ELECTRIC MOTOR-DRIVEN MINE EQUIPMENT AND ACCESSORIES--Table of 

Contents

 

             Subpart B_Construction and Design Requirements

 

Sec.  18.38  Leads through common walls.



    (a) Insulated studs will be acceptable for use in a common wall 

between two explosion-proof enclosures.

    (b) When insulated wires or cables are extended through a common 

wall between two explosion-proof enclosures in insulating bushings, such 

bushings shall be not less than 1-inch long and



[[Page 107]]



the diametrical clearance between the wire or cable insulation and the 

holes in the bushings shall not exceed \1/16\-inch (based on the nominal 

specified diameter of the cable). The insulating bushings shall be 

secured in the metal wall.

    (c) Insulated wires or cables conducted from one explosion-proof 

enclosure to another through conduit, tubing, piping, or other solid-

wall passageways will be acceptable provided one end of the passageway 

is plugged, thus isolating one enclosure from the other. Glands of 

secured bushings with close-fitting holes through which the wires or 

cables are conducted will be acceptable for plugging. The tubing or duct 

specified for the passageway shall be brazed or welded into the walls of 

both explosion-proof enclosures with continuous gas-tight welds.

    (d) If wires and cables are taken through openings closed with 

sealing compounds, the design of the opening and characteristics of the 

compounds shall be such as to hold the sealing material in place without 

tendency of the material to crack or flow out of its place. The material 

also must withstand explosion tests without cracking or loosening.

    (e) Openings through common walls between explosion-proof enclosures 

not provided with bushings or sealing compound, shall be large enough to 

prevent pressure piling.