Rule 60
Earthing Of Electric Devices To Be Used At The Places Of The Consumer
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(1) If electric appliances like water-heater, air-conditioner are installed in  the house of the consumer, provision of earthing shall have to be made for  such appliances by supplying electricity through separate appropriate electric
circuit.
(2) If electric appliances of different metals is to be used in the  house or premises of the consumer, three-pin plug socket shall have to be  installed and such plug socket shall have to be connected with the earthing
system.
(3) The earthing system installed in the house or premises of the  consumer shall have to be in accordance with the technically proper system.