Question

How does earthing offer protection?

Answer 1

Earthing offers protection by connecting the metal casing of an electrical appliance to the earth through a thick copper wire buried deep in the ground. The earth is at zero potential and acts as an electric sink. If the insulation of the appliance fails and the live wire touches the metal casing, the current flows directly into the earth instead of passing through a person's body. Since the earth offers negligible resistance, the current in the circuit rises suddenly to a very high value, which overloads the circuit and causes the fuse to melt. This breaks the circuit, disconnects the faulty appliance, and thus protects the user from a severe electric shock and also prevents the appliance from burning out.