Earthing System

An earthing system is an integral component of electrical installations intended to protect people and equipment against electric shocks, fires, and damage from electrical faults. It incorporates connecting some parts of an electrical installation, like metal parts of appliances and electrical wiring, to the earth. This helps safely discharge excess electricity into the ground in case of a fault, such that the electrical installation works safely.

1.0What is the Principle of Earthing?

The principle of earthing is based on the concept of providing a low-resistance path to the earth for fault currents. In the event of an electrical fault occurring (as in leakage or short circuit of the current), the electrical current runs through the earthing system safely into the ground, preventing any danger to people or equipment. Earthing can of different types:

2.0Types of Earthing 

1. Plate Earthing: In this type of earthing, the plate is connected to the conductor that is linked to the electrical system. The material for the plate is generally copper or a galvanised iron buried in the ground.  
2. Rod Earthing: This is one of the most commonly used Earthing processes. In this, a metal rod is inserted into the ground vertically, this rod is connected to the electrical system by an earthing conductor. 
3. Pipe Earthing: The pipe earthing is typically inserted deeper inside the ground than other electrodes for better grounding. The plate used is of either galvanised steel or copper pipe. 
4. Earthing Through Water Pipe: Although this method is no longer recommended due to safety concerns and poor reliability, Earthing through water is used in the existing water system of a household. 

3.0Earthing and Grounding

Although Earthing and grounding are the two terms that are often used interchangeably, there is a slight difference between them. 

4.0Domestic Earthing Resistance

The resistance of the earthing system offered by the earthing in a domestic electrical installation when a fault current flows through is called domestic earthing resistance. Earthing is achieved when the resistance of the earthing is very low to permit a large fault current to flow safely into the earth without losing any hazardous conditions, for instance, electric shocks or fires.

Importance of Domestic Earthing Resistance: 

1. Free From Electric Shocks: Low earthing resistance allows fault currents to safely reach the ground; thus preventing electric shocks to those persons utilizing electrical appliances.
2. Electrical Equipment Is Protected: Proper earthing with low resistance protects all electrical appliances and equipment from damage through short circuits or leakage currents.
3. Protects Protective Devices: With low earthing resistance, safety elements such as a circuit breaker and fuses are effective in disconnecting the circuit in case of fault to avoid fire hazards.
4. Improves System Reliability: With low earthing resistance, the electrical system is stable and operates effectively, minimizing opportunities for improper grounding that might make equipment malfunction or delay operations.
5. Meets Safety Standards: Maintaining the required earthing resistance (usually less than 1 ohm) ensures compliance with safety regulations and electrical codes, safeguarding the entire installation from electrical hazards.