Abstract: Different line-cord sets connect an electrical device to different supply voltages, assuring that the supply voltage matches the device. Each line-cord set has a uniquely keyed socket and a wall plug. A device receptacle receives the line-cord's keyed socket. An adjustable key on the device mates with the socket's key and rejects nonmating sockets to admit the socket into the receptacle and adjusts the device's input voltage to match the supply voltage.

Abstract: An electric transformer characterized by a transformer tank having an opening with a conducting closure panel in the opening and electrically insulated from the tank, a plurality of first and second conductors of opposite polarities leading from the transformer coil-core assembly with the conductors of opposite polarity comprising forward and return paths. A conducting tubular structure mounted on and extending inwardly from the inside surface of the panel and the return path conductors being connected to the corresponding tubular structures while the forward path conductors extend through the tubular structure and the panel to an external source.