THREE-PIN PLUGS AND SOCKET:
Electrical appliances are provided with a cable having a plug top at one end to connect to the electric supply.The plug top is inserted into the socket, which has three holes with inner walls in the form of metallic tubes.The upper bigger hole in the socket is for earth connection while the hole on the right side is for connection to the live wire and the hole on the left is for connection to the neutral wire of the electric supply[Fig. 1].The plug top has three metallic (usually brass) pins in an ebonite case.
Fig.1
In a plug top,the top pin is for the earthing, the live pin is on the left and the neutral pin is on the right. In good quality plug tops,these are marked as E,L and N respectively.Some times the plug used for low power connection has only the live and the neutral pins.
The earth pin is thicker and longer than the other two.The earth pin is longer so that the earth connection is made first.This ensures the safety of the user because if the appliance is defective, the fuse will blow off. The earth pin is thicker so that even by mistake it cannot be inserted into the live or neutral hole of the socket.
