What will happen if you plug in an overheated cord?

Answer 1

Usually the circuit breaker will trip or fuse will blow to open the circuit. There is some chance the if the breaker or fuse is rated too high the wire to the outlet socket could overheat and cause a fire.

Answer 2

What should (and usually does) happen is the circuit breaker should pop, removing power. However if the overload is unusually large part of the socket may melt before the breaker pops, this can require replacement of the socket before it is safe to use again.

I once had an outlet that melted internally from an overload, it had black scorch marks on both outlets and the cover plate, a plug could not be fully inserted in one of its outlets, and the breaker would not reset until I replaced it. Never fully determined the cause of the overload (it might have been failure of the outlet itself as it was installed in the early 1950s and its construction violates the current electrical code so exact replacement was not possible and anyway while the electrical code permits such old work outlets to stay in use it requires their replacement conform to current code), all my mother said was that "it shot out flames when I plugged in" a radio or clock or something.

Answer 3

It will probably overheat again, and could burst into flames. The insulating cover may be burnt, exposing the wires. This could lead to a short of the wires, or may give you a shock!