Abstract: A heater includes a first heat-generating conductor, a second heat-generating conductor and a shield conductor. The first heat-generating conductor and the second heat-generating conductor are integrally covered with the shield conductor. One end of the first heat-generating conductor and one end of the second heat-generating conductor are electrically connected to each other. When a current is applied from the other end of the first heat-generating conductor, the current flows in the first heat-generating conductor and the second heat-generating conductor in opposite directions. A negative potential -Vn is applied to the shield conductor from a negative potential generating circuit. A positive potential terminal connecting circuit is composed of two diodes. One of the diodes has its anode connected to the positive potential terminal of the negative potential generating circuit and its cathode connected to a first line.

Abstract: An electric heating appliance which is provided with a connecting terminal selecting circuit for the purpose of generating heat in an electric heater in a negative cycle of a commercial AC power source no matter which pole of a plug is connected to a grounding electrode of the power source when the plug is inserted into a plug socket of the power source, the connecting terminal selecting circuit consisting of a delay switch circuit adapted to insulate a heater circuit from the power source for a predetermined period of time when a power source switch is turned on, a heater potential detecting circuit adapted to detect the grounding electrode of the power source, and a change-over switch circuit adapted to connect the anode of an electric power controlling rectifying element for controlling the electric heater to the grounding electrode of the AC power source in accordance with an output signal from the heater potential detecting circuit.