(a) A self-propelled machine, that receives electrical energy through
a portable cable and is designed to travel at speeds exceeding 2.5 miles per
hour, shall have a mechanically, hydraulically, or electrically driven reel
upon which to wind the portable cable.
(b) The enclosure for moving contacts or slip rings of a cable reel
shall be explosion-proof.
(c) Cable-reel bearings shall not constitute an integral part of a
circuit for transmitting electrical energy.
(d) Cable reels for shuttle cars and locomotives shall maintain
positive tension on the portable cable during reeling and unreeling. Such
tension shall only be high enough to prevent a machine from running over its
(e) Cable reels and spooling devices shall be insulated with
(f) The maximum speed of travel of a machine when receiving power
through a portable (trailing) cable shall not exceed 6 miles per hour.
(g) Diameters of cable reel drums and sheaves should be large enough
to prevent undue bending strain on cables.