Importance

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Abstract

An electrical system, such as a system for providing power to an appliance or a building, includes arcing current protection, either in connection with or separate from a ground fault circuit interrupter (GFCI). In one embodiment a sensing lead is located between a power line and a neutral line conveying power to the load, but is not connected to the load. The sensing lead is preferably larger than the power line and neutral line. Also, an integrity checking device may be connected from the sensing lead to the power line to determine continuity of the sensing lead, but current flow through the integrity checking device is limited to a very small magnitude. When an arcing current above a predetermined magnitude occurs in the sensing lead, an SCR is triggered to open the circuit. The sensing lead in such an embodiment may be the ground line of a three line system. In another embodiment, a supplemental winding is placed upon the core of the differential transformer of a GFCI, so that arcing current in the sensing lead above a pre-determined magnitude will pass through the supplemental winding and cause the circuit to be opened. In both embodiments, a test circuit may be included to check operation of the circuit portions responsive to the current in the sensing lead.

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First Claim