We know that electricity is our best friend as well as the worst enemy because if you give it a chance to kill you, remember, it will never disappoint you. Now you know that it’s all about safety and protection.
This is why proper earthing (grounding) is necessary to protect you and the person who touch the metallic body of the machine don’t get electrocuted.
In a 3-pin plug ( as shown in the above fig)
- The Green & Yellow Wire is Earth (IEC & NEC)
- Brown is Live / Line (Black in US)
- Blue is Neutral (White in US)
The earth pin should be the first to connect and the last to disconnect with electric supply. This is why earth pin is longer than the live and neutral pin on 3-pin plugins. Below are the the reason to do so,
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.
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.
This way, earthing is well maintained during the operation for proper safety and protection. Now we know this is why the earth pin is longer as compared to Line and Neutral Pin on a three pin plug.
Why it is Thicker?
First reason, to prevent the wrong way to operate a 3-pin plug and connected electrical machine for the safety purpose. In other words, 3-Pin plug wont be connect to the socket upside down as the earth pin is thicker, so it won’t adjust and fit in another slot made for Neutral or Live Pin in the socket.
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Second reason for thicker pin is that the law of resistance.
- R = Resistance
- ρ = Resistivity
- L = Length of the Conductor
- a = Area of the conductor
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