Why the Earth pin on a plug is Bigger and Longer than other pins?

(5 Min Read)

    We know that the Metal body (Eg: Metal portion of Kettle, Metal Frame of Welding Machine, Outer metal portion of Water Heater) of the appliances  is connected to Earth Pin, If we wrongly inserted the earth pin into the live pin (Phase)  then what will happen....? We do get electric Shock... This is why, it is Bigger... Let see in detail below.

    The main purpose of Earth pin is to safeguard us from Electric Shock from a faulty appliances. If we Powered On the appliances and happen to touch the metal body then the fault current should flow to the ground through the earth pin and not through us... Hence we don't get electrocuted!!!

        

So, why is the earth pin made bigger?

• The earth pin on a plug is Longer than the live and neutral pins. This means the earth pin is the first to connect and the last to disconnect. 
• When inserting the plug, the earth connection is made before the current carrying contacts of the plug become live.
• When withdrawing the plug, the current carrying contacts shall separate before the earth connection is broken. Thus, the earthing connection is always maintained to improve safety.
• Though it is impossible to insert the plug into the socket upside down, one may try to insert the plug top in a misaligned position (for e.g. trying to insert the earth pin into the phase socket with the other two pins further down out of the socket). Hence, the earth pin is made thicker so that even by mistake it cannot be inserted into the live or neutral hole of the socket. This prevents earth pin from establishing an electrical contact with the live terminal.
• Many wall sockets have safety shutters on the live and neutral lines to prevent children from inserting conducting materials which may result in electric shock. Insertion of a longer (earth) pin helps in opening the shutters, facilitating the insertion of other two pins. These are called Earth-pin operated shutters.



Earth-pin operated shutters

• Assumptions like "Larger  Earth Pin Area  having lesser resistance so more current will flow through the Earth Pin " is irrelevant and not applicable to this topic.