Earth Resistance Value Depends

Earth Resistance Value Depends Points : earth resistance value depends, what are the factors on which earth resistance value depends? how earth resistance can be reduced?, multiple earthing systems Earth resistance value depends upon: a) Condition of Soil.
b) Moisture of the soil. c) Temperature of the soil.
d) Depth of the electrode at which it is embedded.
e) Size and spacing of earth electrodes.
f) . Metal of earth plate and earth wire.

The value of earth, resistance can be reduce by increasing moisture of the soil. Thus fresh salt water is poured in earth pit. The value of earth resistance normally should not b more than 1 Ω.

Some of the maximum permissible values of earth resistance for satisfactory results are:
1. Large power stations 0.5ohms
2. Major power stations = 1 .Oohms
3. Small sub-stations = 2.0ohms
4. In all the cases = 0.8ohms Multiple Earthing Systems A TN-C-S system is as the TN-S but the supply cable sheath is also the neutral, i.e. it forms a combined earth/neutral conductor known as a PEN (protective earthed neutral) conductor.

The installation earth and neutral are separate conductors. This system is also known is PME (protective multiple earthing). The resistance should be less than 0.35 ohms.