Pipe Earthing: Brief Overview

 

Pipe Earthing: Brief Overview

Pipe earthing is one of the most commonly used methods for grounding electrical installations. It involves burying a galvanized iron (GI) or copper pipe vertically in a pit filled with salt, charcoal, and soil to provide a low-resistance path for fault currents.

Installation Process (Digging and Setup)

1. Digging the Pit:

   • A pit of approximately 2.5 to 3 meters (8 to 10 feet) deep and 30 cm (1 foot) in diameter is dug in the ground.

2. Inserting the Pipe:

   • A GI or copper pipe (minimum 38mm diameter, 2–3 meters length) is placed vertically in the pit.

   • The pipe has perforations for better moisture absorption.

3. Filling with Salt and Charcoal:

   • The pit is filled with alternative layers of charcoal and salt, which help in improving soil conductivity.

   • The mixture enhances the dissipation of fault current.

4. Connection to the Electrical System:

   • The earthing pipe is connected to the electrical installation using a GI strip or copper wire.

   • A funnel with water is placed at the top of the pipe to maintain soil moisture, which reduces resistance.

5. Covering the Pit:

   • The pit is covered with soil after ensuring all connections are secure.

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Diagram of Pipe Earthing

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Resistance Value at Different Places

The earth resistance of a pipe earthing system depends on various factors like soil type, moisture content, and depth. Typical resistance values in different terrains:

Soil Type	Approximate Resistance (Ω)
Wet/Clayey Soil	0.5 – 5 Ω
Moist Soil	5 – 10 Ω
Dry/Sandy Soil	10 – 25 Ω
Rocky Terrain	Above 25 Ω

• Lower resistance is achieved in moist and clayey soils.

• Higher resistance is found in rocky and sandy soils.

• Adding water, salt, and charcoal helps reduce resistance in dry areas.