30 CFR § 18.20 Quality of material, workmanship, and design.
(a) Electrically operated equipment intended for use in coal mines
shall be rugged in construction and shall be designed to facilitate
inspection and maintenance.
(b) MSHA will test only electrical equipment that in the opinion of
its qualified representatives is constructed of suitable materials, is of
good quality workmanship, based on sound engineering principles, and is safe
for its intended use. Since all possible designs, circuits, arrangements, or
combinations of components and materials cannot be foreseen, MSHA reserves
the right to modify design, construction, and test requirements to obtain
the same degree of protection as provided by the tests described in Subpart
C of this part.
(c) Moving parts, such as rotating saws, gears, and chain drives,
shall be guarded to prevent personal injury.
(d) Flange joints and lead entrances shall be accessible for field
inspection, where practicable.
(e) An audible warning device shall be provided on each mobile
machine that travels at a speed greater than 2.5 miles per hour.
(f) Brakes shall be provided for each wheel-mounted machine, unless
design of the driving mechanism will preclude accidental movement of the
machine when parked.
(g) A headlight and red light-reflecting material shall be provided
on both front and rear of each mobile transportation unit that travels at a
speed greater than 2.5 miles per hour. Red light-reflecting material should
be provided on each end of other mobile machines.