Receptacle and plug therefor

An electrical receptacle defines a receptacle formation of a mating formation pair to prevent a standard plug from establishing electrical connection while permitting an otherwise standard plug defining a corresponding plug formation to be sufficiently inserted to establish an electrical connection. The mating formation pair may include a projection on the receptacle adapted for receipt by a corresponding recess on a compatible plug. Alternatively, the mating formation pair is defined by an opening of the receptacle and a conductor of the plug, each having a cross-sectional height that is reduced from that of a standard receptacle and plug. The mating formation pair is particularly desirable for installation including a receptacle controlled by a dimmer to prevent electrical connection by a standard plug connected to a non-dimmable electrical load.