<P> A lightning arrester ( alternative spelling 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 arrester , the current from the surge is diverted through the arrester , in most cases to earth . </P>
lightning arresters are used in power systems to protect electrical equipments against
the damaging effects of lightning