[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: 30CFR18.41]

[Page 101-102]
 
                       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. 18.41  Plug and receptacle-type connectors.

    (a) Plug and receptacle-type connectors for use inby the last open 
crosscut in a gassy mine shall be so designed that insertion or 
withdrawal of a plug cannot cause incendive arcing or sparking. Also, 
connectors shall be so designed that no live terminals, except as 
hereinafter provided, are exposed upon withdrawal of a plug. The 
following types will be acceptable:
    (1) Connectors in which the mating or separation of the male and 
female electrodes is accomplished within an explosion-proof enclosure.
    (2) Connectors that are mechanically or electrically interlocked 
with an automatic circuit-interrupting device.
    (i) Mechanically interlocked connectors. If a mechanical interlock 
is provided the design shall be such that the plug cannot be withdrawn 
before the circuit has been interrupted and the circuit cannot be 
established with the plug partially withdrawn.
    (ii) Electrically interlocked connectors. If an electrical interlock 
is provided, the total load shall be removed before the plug can be 
withdrawn and the electrical energy in the interlocking pilot circuit 
shall be intrinsically safe, unless the pilot circuit is opened within 
an explosion-proof enclosure.
    (3) Single-pole connectors for individual conductors of a circuit 
used at terminal points shall be so designed

[[Page 102]]

that all plugs must be completely inserted before the control circuit of 
the machine can be energized.
    (b) Plug and receptacle-type connectors used for sectionalizing the 
cables outby the last open crosscut in a gassy mine need not be 
explosion-proof or electrically interlocked provided such connectors are 
designed and constructed to prevent accidental separation.
    (c) Conductors shall be securely attached to the electrodes in a 
plug or receptacle and the connections shall be totally enclosed.
    (d) Molded-elastomer connectors will be acceptable provided:
    (1) Any free space within the plug or receptacle is isolated from 
the exterior of the plug.
    (2) Joints between the elastomer and metal parts are not less than 1 
inch wide and the elastomer is either bonded to or fits tightly with 
metal parts.
    (e) The contacts of all line-side connectors shall be shielded or 
recessed adequately.
    (f) For a mobile battery-powered machine, a plug padlocked to the 
receptacle will be acceptable in lieu of an interlock provided the plug 
is held in place by a threaded ring or equivalent mechanical fastening 
in addition to the padlock. A connector within a padlocked enclosure 
will be acceptable.