Earthing and Electrical Safety - Class IX

Earthing is provided in the building to protect us from electrical shocks due to any leakage of electrical current. It is done to provide safety by minimizing the shock, if someone accidentally touches the faulty wire.

An earthing connection allows the excess electrons to flow into earth. This statement is true. When a wire is attached between earth and conductor, excess electrons flow to earth leaving the conductor neutral.

Potential difference between live wire and neutral wire is $220  V$.

Inside the house, the live and neutral wires are connected to the input terminals of $kwh$ meter, whereas earth wire is connected to body of $kwh$ meter.

Under these conditions if someone by chance happens to touch it then the person will get an electric shock.

In case of earthed appliances, if there is any leakage of current, or the live wire comes in contact with its body then the current flows to the ground through earth wire.

Earthing elements: Materials which are good conductors of electricity. Earthing elements are copper wire, copper plate, salt.

Two or three (2-3) metres hole is dug in the ground for the purpose of earthing.

Earthing, in other term, is also known as grounding.

Earthing ensure flow of charges directly to the ground through the earth wire thus protects us from getting any shock if it passes through us.

 If a person touches the appliance, his body provides a path for current to flow to earth which is at zero potential.Thus, person may get severe shock which may prove fatal. Hence, fuse is connected to live wire so that if it melts, the appliance is no longer connected to the high potential of the supply and possibility of electric shock is eliminated.

Earth wire is the insulated green coloured copper wire which is connected to a metal plate deep inside the earth near the house. It is used as a safety measure. It is kept at zero potential by connecting it to the ground, thus, providing a low-resistance conducting path for the current. When by electric fault, if current flows through the metallic body of electric appliance and we touch it, then current finds the lower resistance path of earth wire than our body. So, current flows through earth wire only and we remain safe.

In case of an earthed appliance, if there is any leakage of current or the line wire comes in contact with its body, then the current flows to the ground.

In an electrical circuit, the earth is considered as having $0(zero)$ potential.

The earth terminal is connected to the metal casing so that the current goes through the earth wire instead of causing an electric shock. A strong current surges through the earth wire because it has a very low resistance. This breaks the fuse and disconnects the appliance

The earth wire is connected to the outer casing of the appliance because the earth wire can carry leaked charges to the ground.The outer surface is usually made conducting and an earth wire takes the excess charge from the body to the earth which is a charge sink,thus preventing us from getting a shock due to charge buildup.