Question

why the earth pin is thicker and longer than the live and neutral wire

Answer 1

The following are the advantages of using thick and longer earth wire:

i) It does not allow incorrect plugging in a three pin socket.
ii) It provide the sufficient contact area with the hollow pin of the socket which reduces the contact resistance of the earth wire.
iii) while plugging in ,the earth wire makes earlier contact to the socket as compared with other two. Thus the metallic body of the appliances makes contact with the earth before energizing. Similarly, when removing from the socket it loses it contact the last.
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