(b) Lighting fixtures may be installed on self-propelled machines or
may be stationary lighting fixtures.
(c)(1) Electrically operated lighting fixtures shall be energized by
direct current, or by sinusoidal full wave alternating current not less than
50 cycles per second (100 pulses per second), or by an equivalent power
source that causes no greater flicker.
(2) Alternating current circuits supplying power to
stationary lighting fixtures shall contain conductors energized at voltages
not greater than 70 volts to ground. Alternating current circuits, energized
at 100 volts or more and used to supply power to staionary lighting fixtures,
shall originate at a transformer having a center or neutral tap grounded to
earth through a proper resistor, which shall be designed to limit fault
current to not more than 5 amperes. A grounding circuit in accordance with
§75.701-4 shall orignate at the grounded terminal of
the grounding resistor and extend along with the power conductors and serve
as a grounding conductor for the frames of all equipment receiving power
from the circuit. The ground fault current rating of grounding resistors
shall meet the "extended time rating" set forth in the Institute of
Electrical and Electronics Engineers, Inc. Standard No. 32 (IEEE Std.
32-1972) which is hereby incorporated by reference and made a part hereof.
The incorporated publication is available for examination at each MSHA Coal Mine Safety and
Health district office and may be obtained from the Institute of Electrical and Electronics Engineers, Inc.,
Publications Office, 10662 Los Vaqueros Circle, P.O. Box 3014, Los Alamitos, CA 90720-1264 Telephone: 800-272-6657 (toll free); http://www.ieee.org.
(3) Machine-mounted lighting fixtures shall be
electrically grounded to the machine by a separate grounding conductor in
compliance with §75.701-4.
(d) Direct current circuits in excess of a nominal voltage of 300
volts shall not be used to supply power to stationary light fixtures.
(e) Cables conducting power to stationary lighting fixtures from both
alternating and direct current power sources, other than intrinsically safe
devices, shall be considered trailing cables, and shall meet rhe requirements
of Subpart G of this part. In addition, such cables shall be protected
against overloads and short circuits by a suitable circuit breaker or other
device approved by the Secretary. Circuit breakers or other device approved
by the Secretary protecting trailing cables receiving power from resistance
grounded circuits shall be equipped with a ground trip arrangement which
shall be designed to deenergize the circuit at not more than 50% of the
available fault current.
(f) Before shunts are removed from blasting caps, lighting fixtures
and associated cables located in the same working place shall be deenergized.
Furthermore, lighting fixtures shall be removed out of the line of blast and
not less than 50 feet from the blasting operation unless otherwise protected
against flying debris.
(g) Lighting fixtures shall be designed and installed to minimize
discomfort glare.
