Abstract: There is provided an improved interlock mechanism for a plug and receptacle. The receptacle houses an electrical circuit breaker which controls the power to a set of contacts in the receptacle. A pair of spring biased ears are mounted on the outside of a barrel portion of the receptacle which receives the plug and locks the plug to the receptacle. A pair of rods are mechanically coupled to the circuit breaker and adapted to be received in corresponding holes in the ears when the plug is in the receptacle and the power is switched on. However, when the plug is not in the receptacle, these rods will abut against a solid surface on the ears during an attempt to switch the power on. Thus, power may be switched on only when the plug is received in the receptacle; furthermore, the plug may not be retracted while the power is on.