[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: 30CFR18.47]

[Page 103]
 
                       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. 18.47  Voltage limitation.

    (a) A tool or switch held in the operator's hand or supported 
against his body will not be approved with a nameplate rating exceeding 
300 volts direct current or alternating current.
    (b) A battery-powered machine shall not have a nameplate rating 
exceeding 240 volts, nominal (120 lead-acid cells or equivalent).
    (c) Other direct-current machines shall not have a nameplate rating 
exceeding 550 volts.
    (d) An alternating-current machine shall not have a nameplate rating 
exceeding 660 volts, except that a machine may have a nameplate rating 
greater than 660 volts but not exceeding 4,160 volts when the following 
conditions are complied with:
    (1) Adequate clearances and insulation for the particular voltage(s) 
are provided in the design and construction of the equipment, its 
wiring, and accessories.
    (2) A continuously monitored, failsafe grounding system is provided 
that will maintain the frame of the equipment and the frames of all 
accessory equipment at ground potential. Also, the equipment, including 
its controls and portable (trailing) cable, will be deenergized 
automatically upon the occurrence of an incipient ground fault. The 
ground-fault-tripping current shall be limited by grounding resistor(s) 
to that necessary for dependable relaying. The maximum ground-fault-
tripping current shall not exceed 25 amperes.
    (3) All high voltage switch gear and control for equipment having a 
nameplate rating exceeding 1,000 volts are located remotely and operated 
by remote control at the main equipment. Potential for remote control 
shall not exceed 120 volts.
    (4) Portable (trailing) cable for equipment with nameplate ratings 
from 661 volts through 1,000 volts shall include grounding conductors, a 
ground check conductor, and grounded metallic shields around each power 
conductor or a grounded metallic shield over the assembly; except that 
on machines employing cable reels, cables without shields may be used if 
the insulation is rated 2,000 volts or more.
    (5) Portable (trailing) cable for equipment with nameplate ratings 
from 1,001 volts through 4,160 volts shall include grounding conductors, 
a ground check conductor, and grounded metallic shields around each 
power conductor.
    (6) MSHA reserves the right to require additional safeguards for 
high-voltage equipment, or modify the requirements to recognize improved 
technology.