A locking assembly for selectively locking a female electrical receptor with an electrical male plug connector is disclosed. The male plug has a plurality of prongs with apertures, and female receptor has prong-receiving contact members with openings that are aligned with the apertures when the plug is connected with the receptor. The locking assembly can have a pair of caps with conical projections that fit into the openings in the contact members and apertures of the prongs. A spring-loaded actuator button moves the caps in and out of engagement with the contact members and the prongs. Several embodiments of the locking assembly are disclosed.