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Earth Resistance & Acceptable Earth Resistance value in India



What is Earth Resistance?

The resistance of the earth electrode to the current flow into the earth is known as an earth resistance. The resistance between the earth and the earthing plate is measured through a potential fall method.

Numerically, it is equivalent to the ratio of the earth electrode’s potential to the current disappeared by it. The resistance between the earthing plate and the earth is assessed through the potential fall method.

The earthing resistance value is based upon the soil resistivity, construction design, and climate-related condition. Moisture in soil plays a critical role in the resistivity of the soil. Different types of codes indicate the desired value of an earthing system.

Acceptable Earth Resistance Value in India

The acceptable earth resistance value in India is are follows:-

US AID | Earthing Practices of India by MVS Brinch

(1) Earth Resistance of Power Station 0.5 ohms
(2) Earth Resistance of EHT Sub-station 1.0 ohms
(3) Earth Resistance of 33 KV Stations 2.0 ohms
(4) Earth Resistance of D/t Structure 5.0 ohms
(5) Tower Foot Resistance 10.0 ohms


 Chapter 4 of IEEE standard 142-2007

Resistance suitable for industrial plant


Sub-stations, buildings & large installations

1 ohm to 5 ohms


 IS 2309: 1989, Cl 12.3.1 Page 32 and BS 7430:1998 

Cl 9.4.3 Lightning arrestors earth resistance for Protection of allied
structures & buildings
10 ohms


 Guide to control Undesirable Static Electricity 

Lightning arrestors earth resistance for Protection Of allied structures
and buildings
10 ohms


 IS 2689:1989, Table 4 page 28 (Reaffirmed March 2010)

Lightning arrestors eath resistance for Protection of buildings and
allied structures
10 ohms
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