Pennsylvania Statutes Title 52 P.S. Mines and Mining § 70-1127. Trolley installation

(a) All trolley wires and feeder lines installed on underground haulage roads shall be placed as far to one side of the passageway as is practicable, but not less than six inches outside of line of rail. The trolley hangers shall be securely supported, and be so spaced that the wire may become detached from any one hanger without creating a shock hazard, and not more than twenty-four feet apart.

(b) Trolley wires and trolley feeders shall be kept taut and not be permitted to touch the roof, ribs, timbers or any combustible material.

(c) In gassy mines trolley and feeder wires shall not extend beyond one hundred feet outside the last open crosscut.

(d) All branch trolley lines shall be fitted with either a trolley switch, circuit breaker, or section insulator and line switch, or some other device that will allow the current to be shut off from such branch headings. Switches or circuit breakers shall be provided on haulage roads to deenergize all trolley and feeder lines at intervals not to exceed two thousand feet.