Portable electric hair dryer with electric shock protection circuit

Abstract

A portable electric hair dryer includes an electric heater and blower forming a load circuit energized from a pair of power feeder lines connected to a source of AC power. A zero phase-sequence current transformer is electrically coupled to the power feed lines between the connection thereof to the power source and the load circuit to serve as a current leakage detector. An electricaly conductive heater enclosure disposed within the housing of the hair dryer receives the heater and is electrically isolated from the power feed line serving as the hot line. The heater enclosure is electrically connected to the power feeder line serving as the neutral line by a ground wire extending between the heater enclosure and the point at which the zero phase-sequencing transformer is coupled to the power feeder lines to define a leakage current path between the hot line and the heater enclosure should the hair dryer be dropped in water. Upon detection of leakage current the detector operates a manually resettable switch associated with the power feeder lines to disconnect the load circuit from the AC power source, thus eliminating the danger of electrical shock and ensuring safe retrieval of the hair dryer from the water. The leakage detector and switch may be incorporated into a plug provided on the connecting end of the power feeder lines or they may be incorporated into a wall mounted holder for the hair dryer.