Generally, devices like table lamps, mobile adapters, television points, mixer-grinders, food processors, etc. have two pin plugs. But if you see appliances like washing machines, air conditioners, refrigerators, you will notice that they have three pin plugs. Why does this difference arise? In fact, if you read the listed appliances again, you will get a clue on why they use different plugs.
The answer is quite clear actually — the devices that draw more current from the supply mains need three pin plugs. They perform more heavy duty operations and the third pin is an added protection for the greater amount of current that they draw.
Let us understand this better.
The two pins that are mandatory on any socket are called as the live point (or the phase point) and the neutral point. These are the points where the live and neutral wires of the plugs are put. Any electrical circuit needs to be a closed network. Here, the live wire brings the electric current from the mains and the neutral wire takes it back. Thus, the circuit gets completed.
However, if the appliance in question is a heavy duty appliance, it will try to draw more current from the mains. This will cause more charge to flow into the device, and there is a likelihood that the charge may stay on the body of the device itself. This can be dangerous. If anyone touches the body of the device, they could get an electrical shock.
The third pin is an earth pin. It helps by carrying the excess charge to the earth. It is attached to an underground plate conducts all the extra electrons and sends them to the earth.
You could visit Electricien Maisons Laffitte for more information such as this.