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Chapter 1 of 12 • Page 1 of 248🔒 Protected PDF • Watermarked
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What are the method of earthing?
Plate earthing
Pipe earthing
Coil earthing
All of above
All of above
Quick Summary: Earthing methods serve to provide a low-resistance path to the ground for fault currents, ensuring the safety of personnel and equipment. The choice of method, such as plate, pipe, or coil earthing, depends primarily on soil resistivity, moisture content, and the magnitude of the fault current to be handled.
Earthing methods serve to provide a low-resistance path to the ground for fault currents, ensuring the safety of personnel and equipment. The choice of method, such as plate, pipe, or coil earthing, depends primarily on soil resistivity, moisture content, and the magnitude of the fault current to be handled.
Re=2πLρ[ln(d4L)−1] — Resistance of a pipe electrode of length L and diameter d
ρ=2πsR — Wenner's method for soil resistivity calculation with spacing s
All earthing systems rely on the principle of potential equalization and fault current dissipation. By burying a conductive electrode (plate, pipe, or coil) in the earth, the system utilizes the large electrical capacity of the Earth to absorb discharge. The effective resistance is governed by the electrode's surface area and the surrounding soil's resistivity (ρ=LRA), where R is the earth resistance, A is the area of contact, and L is the depth.
Plate earthing uses a metal plate (copper or GI) buried at a depth of at least 3 meters.
Pipe earthing is the most common method in India, utilizing a perforated GI pipe.
Coil earthing is typically used in areas with very high soil resistivity or where deep excavation is not feasible.
The ground resistance should ideally be kept as low as possible, typically below 1 ohm for large stations.
Protects equipment from lightning surges and voltage spikes.
Prevents fire hazards by clearing earth faults quickly.
Ensures stable voltage reference for electrical systems.
Earth resistance increases during dry seasons due to reduced soil moisture.
Electrodes are susceptible to corrosion over time, increasing resistance.
Requires periodic maintenance and salt-charcoal treatment to sustain efficiency.
Distribution substations
Residential building wiring
Transmission tower grounding
Industrial machinery protection
| Feature | Plate Earthing | Pipe Earthing |
|---|---|---|
Depth of Burial | Min 3m | Min 2.5m - 3m |
IS: 3043 is the standard code for Earthing in India.
All mentioned methods are standard practices recognized by the Bureau of Indian Standards (BIS).
D is correct — Plate, pipe, and coil earthing are all established methods used to provide a safe discharge path to the ground for fault currents.
Always remember that earthing rod/pipe length is the most critical parameter in reducing resistance; doubling the length is more effective than doubling the electrode diameter.