30 C.F.R. § 57.4561
Stationary diesel equipment underground
Stationary diesel equipment underground shall be—
(a) Supported on a noncombustible base; and
(b) Provided with a thermal sensor that automatically stops the engine if overheating occurs.
Stationary diesel equipment underground shall be—
(a) Supported on a noncombustible base; and
(b) Provided with a thermal sensor that automatically stops the engine if overheating occurs.