.-Energy shall not be transmitted into a mine at a voltage exceeding 11000 volts and shall not be used therein at a voltage exceeding 6600 volts:Provided that:(a)where hand-held portable apparatus is used, the voltage shall not exceed 125 volts;(b)where electric lighting is used:-(i)in underground mines, the lighting system shall have a mid or neutral point connected with earth and the voltage shall not exceed 125 volts between phases;(ii)on the surface of a mine or in an open cast mine, the voltage may be raised to 250 volts, if the neutral or the mid point of the system is connected with earth and the voltage between the phases does not exceed 250 volts;(c)where portable hand-lamps are used in underground working of mine, the voltage shall not exceed 30 volts;(d)where any circuit is used for the remote control or electric inter-locking of apparatus, the circuit voltage shall not exceed 30 volts:Provided that in fixed plants, the said voltage may be permitted upto 650 volts, if the bolted type plug is used.]
