PURPOSE: To prevent the deterioration of anarrester and the damage to an insulating tube by connecting a pair of zinc oxide arresters in seriese with an insulating member interposed therebetween, and by arranging a meltable body which melts and breaks when fault current is generated and a pair of electrodes for transferring the generated arc.

CONSTITUTION: One end of zinc oxide type 4a, 4b which are connected together in seriese with an insulating member 5 interposed therebetween is connected to an iron tower 1, and the other end of the zinc oxide type arresters is connected through first horn-like electrodes 13 to a transmission line 3. Second horn-like electrode 14 are arranged in parallel with the insulating member 5, a meltable body 22 which can melt and break when electric current above a certain level passes through it is interposed between the electrodes, and third horn-like electrodes 15 are arranged in parallel with the arresters 4a, 4b. Thus, when an overvoltage is generated by lighting stroke, the electrodes 13 discharge and then the electrodes 14 discharge so that resistance of each arrester 4a, 4b is lowered. When fault current is generated in the system the meltable body 22 melts and breaks, the arc generated at the electrodes 14 is transferred to the third electrodes 15, and the electric current is by-passed.