Safety circuit and socket construction

Abstract

An electrical socket and associated circuitry is provided wherein current can flow to the socket only when a load device is in the socket and a normally open, momentary 'make' switch is closed. The circuitry includes a relay for actuating a switch in parallel with the momentary make switch, which relay is energized upon closure of the momentary make switch and remains energized so that current will continue to flow to the socket until a normally closed, momentary 'break' switch is opened. Current cannot flow through the socket with the load device removed even if one should touch the socket except in the unlikely event the make switch is closed. Several embodiments are disclosed wherein no current can flow through the socket unless at least three socket parts are engaged. In one form of socket, the socket base contact is divided into two parts, both of which must be engaged in order for the relay to remain energized. In another form the socket shell contact is divided into two parts and again both parts must be engaged for the relay to remain energized. Other sockets are illustrated wherein the presence of a load device is sensed by switch means which may include the socket base contact. Circuits for use with polarized plugs are disclosed and a form of circuit for use with an unpolarized plug is also disclosed. Further, a circuit utilizing a rectifier and a low voltage relay is also disclosed wherein the make and break switches are in low power lines.