Well, let me explain to you.
If someone by mistake inserts the earth pin in the phase
then the person who is holding or standing near the device will get an electric shock
that’s why the earth pin is thicker compared to neutral and phase.
By doing this, we can’t insert the earth pin in phase.
Why earth pin is longer?
Because when we insert the plug into the socket,
earthing will be first connected to the machine/device because the pin is longer in size which makes the machine safe.
That’s why the earth pin is longer and thicker.
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