Abstract: An electrical power distribution system is provided with an elongate track and a plurality of power tap assemblies that are engageable with the track. The power tap assemblies may be moved to any desired location along the track. Power may be fed into the track through one of the assemblies and taken out of the track through another of the assemblies. Receptacles may be mounted to one or more of the power tap assemblies. A latch system can hold the power tap assemblies in (1) a fully inserted, electrically engaging orientation and (2) an electrically disconnected orientation wherein the components are still supported on the track. The components employ spring terminals which establish electrical contact through a surface-to-surface butt engagement with a conducting member. Mechanical key systems are provided for preventing improper mounting of the components on the track and for preventing the connection of more than one power in-feed to the track.