Lightning Arrestor

A lightning arrestor (also called lightning diverter) is a device used on electric power systems and telecommunication systems to protect the insulation and conductors of the system from the damaging effects of lightning. The typical lightning arrester has a high-voltage terminal and a ground terminal. When a lightning surge (or switching surge, which is very similar) travels along the power line to the arrestor, the current from the surge is diverted through the arrestor, in most cases to earth.

Lightning arresters are used to protect electric fences. They consist of a spark gap and sometimes a series inductor. Lightning arresters can form part of large electrical transformers and can fragment during transformer ruptures. High-voltage transformer fire barriers are required to defeat ballistics from small arms as well as projectiles from transformer bushings and lightning arresters.