The double earthing is used for

The double earthing is used for

Right Answer is:

3-phase machines


Double earth is used for a 3-phase machine and equipment. This gives minimum resistance to the flow of the whole current of that apparatus in case of short circuit, leakage, etc. When double earth is used, there is an advantage of redundancy.

For providing better safety, it is advisable to provide two separate earth wires, from two separate earth electrodes, connected to the same metallic body of the equipment at two different points. This is known as double earthing.

Double earthing is essential, as per Indian Electricity Rule, for metallic bodies of large rating equipment such as transformers, motors, etc. working at 400 V and above or 3-phase machines.

Advantages of double earthing are as follows:

1. Surety of safety, because if at any time, one earthing is ineffective, then another will provide earth path to fault current.

2. As the two earth wires are in parallel, the effective resistance from equipment to earth electrode is reduced.

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