(a) Heavy-duty diesel-powered equipment includes -
(1) Equipment that cuts or moves rock or coal;
(2) Equipment that performs drilling or bolting functions;
(3) Equipment that moves longwall components;
(4) Self-propelled diesel fuel transportation units and self-propelled lube units; or
(5) Machines used to transport portable diesel fuel transportation units or portable lube units.
(b) Light-duty diesel-powered equipment is any diesel-powered equipment that does not meet the criteria of paragraph (a).
(c) For the purposes of this subpart, the following equipment is considered attended:
(1) Any machine or device operated by a miner; or
(2) Any machine or device that is mounted in the direct line of sight of a job site located within 500 feet of such machine or device, which job site is occupied by a miner.
(d) Diesel-powered ambulances and fire fighting equipment are a special category of equipment that may be used underground only in accordance with the mine fire fighting and evacuation plan under § 75.1502.