Question

Why is it essential to earth electrical appliances having metallic body?

Answer 1

Because metallic wire (if any wire inside them is touching the body) can produce electricity to the hole body, which is unsafe for us. so it is important to earth electrical appliances with metallic body so that the current goes to the earth and do not hit us.

Answer 2

It is not essential but it is always preferred as it never harms you to take precautions.