what do you mean by earthing??
Earthing is the proper connection of exposed metal parts of an electrical circuit to the ground. It is accomplished by thick copper wires. Earthing protects the appliances and human beings in case of insulation fail or accidental short circuit. When the live wire touches the earth wire, large current flows through it and causes the fuse to blow off or circuit breaker to trip and thereby protecting the appliance as well as users.
In electricity supply systems, an earthing system defines the electrical potential of the conductors relative to the Earth's conductive surface. The choice of earthing system can affect the safety and electromagnetic compatibility of the power supply, and regulations can vary considerably among countries. Most electrical systems connect one supply conductor to earth(ground). If a fault within an electrical device connects a "hot" (unearthed) supply conductor to an exposed conductive surface, anyone touching it while electrically connected to the earth (e.g., by standing on it, or touching an earthed sink) will complete a circuit back to the earthed supply conductor and receive an electric shock.