CrazyEngineers Archive
Old, but evergreen and popular discussions on CrazyEngineers, presented to you in read-only mode.
@Vignesh Viky • 17 Apr, 2015
What is the difference between a three pin plug and a two pin plug?
And what are those three pin used for?
Expecting a detailed answer...
@lal • 17 Apr, 2015 What did Google and Wiki say when you asked?
@jeshukb09 • 17 Apr, 2015
What is the difference between a three pin plug and a two pin plug?
And what are those three pin used for?
Expecting a detailed answer...
Hi vigneshsekar007, the question you asked is very basic and many people might be having this doubt.
Basically, we use three pin plugs for those devices which are having inductive type elements as a part of the circuit. Due to this inductive element, there might some energy stored in it. It is necessary for this energy to be eliminated or neutralized. The third pin which is called ground pin is used for that purpose.
The additional pin in a three pin plug as compared to a two pin plug is the GROUND pin. It is the pin with larger cross section (diameter/thickness). The other two pins are 'Phase' and 'Neutral'.
@Vignesh Viky • 18 Apr, 2015 thanx. That was a satisfying answer
@lal • 18 Apr, 2015 I cannot fully agree with you. Earthing of an equipment is not done to neutralise energy stored in inductive loads. Earthing is done in any electrical appliance primarily to ensure safety of the person who uses it.

In case an insulation failure or fault occurs inside the equipment, the live wire might come in contact with the conductive covering/body of the equipment and pose a threat for electric shock for anyone touching it if it is not grounded. Grounding ensures that the high potential on the equipment body is brought to earth potential (0V) by providing a low resistance path, thus protecting from a possible electric shock.

The 'Earth pin' in a three pin plug is bigger than the live and neutral pins for a reason. Being s larger diameter, Earth pin would provide a comparitively lower resistance for current flow than the rest. Apparently a higher gauged wire is normally used for grounding.

Chances are that the protective devices employed in the circuit like fuse, MCB or RCCB blow/trip during the event of an earth fault.
@kavivarmen rajalingam • 24 Sep, 2015 can anyone please explain to me why does a 2 pin plugged can be plugged in both ways? why nothing happens when we plug them in a reversed manner?

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