PURPOSE:To prevent the surface flash over through the surface dirt of a nonlinear resistor due to a lightning surge by joining and fixing a column, formed from a material having a non-linear voltage-current characteristic and having its one end abutting the voltage applied side and the other end abutting earth side, and insulating creases formed of porcelain with an inorganic material. CONSTITUTION:When a lightning surge current enters an electric wire 5, the lightning surge current flows through an insulator column 1 formed of a nonlinear resistor to base fittings 8, and is discharged to the earth side of an arm 11, etc. The continued current in the line following to the lightning surge is interrupted by the non-linear resistor constituting the column 1 so that an earthing accident, etc., are prevented. In addition, an undue lightning surge current unable to be discharged by the column 1 discharged to the base fittings 8 via an electrically conductive layer 14 on the insulator surface. As a result, the damage to the insulator owing to the arc of the non-linear resistor is reduced. Further, the non-linear resistor can be mechanically strengthened by providing a through-hole 1a in the column 1 and inserting a reinforcing member 16 such as FRP into the hollow part thereof and fixing it therein, and fixing the lower end of the reinforcing member 16 together with the column 1 to the base fittings 8.
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