Lightning Arresters

a typical lightning arrester, also called surge arrester, comprises a high voltage terminal made of copper of aluminum mounted on top of a building. It is electrically connected to the ground terminal through a wire to protect the building in the event of lightning. If lightning strikes the building, it will preferentially strike the lightning rod and be conducted harmlessly to ground through the wire, instead of passing through the building where it could start a fire or cause electrocution. Lightning arresters can be commonly seen mounted on tall buildings, monuments, towers, water tanks etc.
a very important point worth noting in this regard is that a lightning arrester or lightning protection system as a rule never stops the action and effects of lightning. However, it provides ample protection and insurance against the damage to the building and electrical devices.