What is Earthing??!! | Electrical Engineering Theory

With the half of low resistance wire , the process of transferring the immediate discharge of the electrical energy directly to the earth is called electrical earthing.

Definition according to Indian electricity rules:

"The earthed means connection with the general mass of the earth in such manner as to ensure at all times an immediate discharge of energy without danger."

What is Earthing??!! | Electrical Engineering Theory

Objectives of Electrical Earthing

Save the human life from the electric shock

Protection of all machine from the lightning

Protection of big buildings from atmospheric lightning

For maintain constant line voltage.

The circuit of Electrical Earthing is shown in below image

Circuit Diagram of Electrical Earthing

When anyone touch the metallic body of any part having perfect insulation, then two parallel paths are formed.

When insulation resistance is very high as compared to the appliance resistance, so all the current flows from the appliance resistance and no current can flow through the human body

When earth fault occurs phase wire directly comes in contact with the outer body and the insulation resistance is reduced to zero.

Now the body resistance is make in parallel with the appliance resistance. So heavy current flows through the human body and operator gets a severe shock.

When earth resistance is comes in parallel with the appliance resistance and body resistance then the it's called outer frame of the appliance is properly earthed.

Since earth resistance is very small as compared to body resistance then the almost current flows through the earthed resistance and No current can flow through the human body, So this way human is protected from the electric shock.