A plurality of interchangeable, electrically powered, modules and receptacles for use therewith are provided. The interchangeable electrically powered modules are configured and capable of providing a variety of electrical and electronic devices. Each receptacle is configured to be secured to and supported by an otherwise conventional electric back box. The receptacles preferably utilize a bayonet mount receptacle which is standardized for the entire system and which accommodates each and every module in a twist-lock mounting system. Each module includes a cooperating bayonet mount attachment for use with the receptacle bayonet mounts. The use of a bayonet mount attachment for the modules to the receptacle provides a standardized power coupling for the module devices which may be connected by a simple insert and partial turn locking action.