(d) Trailing Cables. (1) Trailing cables for face equipment shall be safely and efficiently insulated by a flame resistant material. They shall be approved by the secretary.

(2) Cables for hand held electric tools shall be three conductor type, specially flexible, heavily insulated by flame resistant material and effectively protected from damage; the free end of cable to have a weatherproof, lock type, three pronged polarized plug, with a suitable receptacle for attachment.

(3) Each trailing cable in use shall be examined daily by the machine operator for abrasions and other defects while cable is de-energized. He shall also carefully observe the trailing cable while in use, and shall at once report any defect to the mine official in charge.

(4) In the event of the trailing cable in service breaking down or becoming damaged in any way, or of its inflicting a shock upon any person, it shall be put out of service at once. The faulty cable shall not be used again until it has been repaired and tested by a properly authorized person.

(5) The trailing cable shall be divided at the machine in which it is supplying power, but only for such length as is necessary for making connection to the machine terminals, and the cable, with its outer covering complete, shall be securely clamped to the machine frame in a manner that will protect the cable from injury and prevent any mechanical strain being borne by the single ends connected to the machine terminals.

(6) No more than five temporary splices shall be made in any trailing cable. After the fifth such splice is made, the cable shall be changed before the machine is operated on the following shift. Trailing cables on equipment without cable reels shall have no temporary splices within fifty feet of the machine before the machine is operated on the following shift.

(7) Trailing cables shall be hung or adequately protected to prevent their being run over and damaged by mobile machinery.

(8) Trailing cables on off-track equipment shall contain a safety ground conductor which shall be solidly connected to the machine frame. The safety ground conductor shall have a cross sectional area of at least fifty percent of that of a single power conductor.

(h) Detection of Gas. (1) In working places where explosive or noxious gas is likely to be encountered, an approved safety lamp for the detection of such gas shall be provided for use with each machine when working, and should any indication of gas appear on the flame of the safety lamp, the person in charge shall immediately stop the machine, cut off the current at the nearest switch, and report the matter to a mine official.

(2) In any gassy mine no electrically operated face equipment shall be taken in by the last open breakthrough until the machine operator shall have made an inspection² for gas in the place where the machine is to work, unless such examination is then made by some other competent person authorized or appointed for that purpose by the mine foreman. If any explosive gas is detected in the place by an approved safety lamp, the machine shall not be taken in. The place shall be dangered off until the gas has been removed or rendered harmless.

(3) No electrically operated face equipment shall be continued in operation in a gassy mine for a longer period than half an hour without an examination as above described being made for gas, and if gas is found the current shall at once be switched off the machine, and the trailing cable shall forthwith be disconnected from the power supply.

(4) The person finding gas shall at once report the fact to the mine foreman or³ assistant mine foreman and the machine shall not again be started in such place until the mine examiner or a person duly authorized by the mine foreman has examined it and pronounced it safe.

(5) In any gassy portion of a mine, if any electric sparking or are be produced, outside of a coal-cutting or other portable motor, or by the cables or rails, the machine shall be stopped, disconnected from the power supply, and not be worked again until the defect is repaired and the occurrence shall be reported to a mine official.