If too many electrical appliances of high power rating are switched on at the same time, they draw a large current from the circuit. This is called overloading.
If the live wire and neutral wire come in contact either directly or via conducting wire, the situation is called short circuiting.
To avoid the risk of electrical shock the metal body of the appliances is earthed. Earthing means to connect the metal case of the appliance to earth by a means of a metal wire called earth wire.
