Question

why are electric switch or plug made of thermosetting plastic

Answer 1

Because it is a non conductor of electricity so that we will not get any electric shock

Answer 2

hey mate......
here is your answer .......

this is because thermosetting plastics are insulators i.e. they doesnot conduct electricity and prevents from electric shocks as well and are bad conductors of heat also.
therefore its an excellent material to be used in electrical devices and appliances.

hope it helps :)