PURPOSE: To improve safety by forming a heat emitting wire with lamination of core material, heat emitting conductor, thermosetting resin material, signal wire, insulating layer and the like, and connecting a temperature fuse operated through a thyristor, and a current fuse thereto.

CONSTITUTION: When a signal wire 4 is cut after, for example, it is repeatedly stepped on, electric potential at a connection point between a resistor R1 and the wire 4 increases, gate potential increases through connection points of resistors R2, R3, and a thyristro SCR is ON. Then current flows into a heat emission resistor R0 to fuse and cut thermocoupled temperature fuse TF, stopping current supply. When a heating conductor 2 is cut, wire cut arc fuses a thermosetting resin material 3 to flow large current, fusing a current fuse CF, then branch voltage due to resistors R2, R3 put the thyristor ON to shut out current supply. Similarly when the resin material 3 is fusion cut by heat from the outside by such as an iron or the like, current supply is shut out to prevent abnormal high temperature, so the safety can be remarkably improved.