Pennsylvania Statutes Title 52 P.S. Mines and Mining § 690-318. Stationary motors

Every stationary motor underground, together with its starting equipment, shall be protected by a fuse or circuit-breaking device on each ungrounded pole and by switches arranged to entirely cut off the power from the motor. The devices shall be installed in a convenient position near the motor, and every stationary underground motor of 100 brake horsepower or over shall be provided with a suitable meter to indicate the load on the machine.