Why is Earth Pin Thicker and Longer in a 3-Pin Plug?

Why is Earth Pin Longer and Larger in a 3-Pin Plugs ?

We know all the electrical appliances with metal bodies should be properly earthed and grounded. And the reason for this earthing is prevent the human being from electric shock if human touch live parts of appliances having short/leakage current in it.

3 Pin socket

Why the earth pin is Longer in 3 Pin Plugs ?

The earth pin should be the first to connect and the last to disconnect with electric supply to make first connection with earthThis is why earth pin is longer than the live pin and neutral pin on 3-pin plugs.

Please check below points also :

  1. When we insert a 3-pin plugin into a 3-pin socket, the earth pin is the first to make a contact with the socket as compared to the Live and Neutral Pins to connect the earth connection on proior for safety.
  2. The earth pin is the last to disconnect from the socket when removing the plug from the socket. i.e. Line and Neutral disconnect first and then the earth pin beacuse it should be connected to earth unless live parts leave connection with phase.

Why the earth pin is Thicker in 3 Pin Plugs ?

First benefit of Thicker pin is to prevent the wrong way to operate a 3 pin plug.

And second reason is law of resistance

R = ρ (L/a)   … [ Law’s of Resistance)

And we know

R denotes as Resistance

ρ denotes as resistivity

L denotes as Length of conductor


a denoted for area of conductor

Now Lets discuss about the above formula

Resistance is inversely proportional to the area of the conductor. i.e. thicker of the conductor, lesser is the resistance. Means if increase the dia of condcutor resistance will reduce.

So if in any case, whenever a wet body having low resistance touches the metallic body of the machine where leakage current exist. Current will flow through it as it find easiest way (having very low resistance) to complete the path. So there is still a chance of electric shock in the above mentioned case. current will flow from the earth which is having low resistance.

Why there is a cut or split in the electrical plug ?

When excessive current flow through a plug/conductor there is a bad effect on thermal expansion. So, the pins of the electrical plug are cut so that they cannot change their shape when heated. Whenever electricity flows through such pins, the power is split into two parts due to the incision, so that they do not heat up quickly.


Thanks for  Reading

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