Lightning Arrester is a protective device for electrical equipment that reduces excessive voltage resulting from lightning to a safe level by grounding the discharge. This is an electrical device inserted in a power line to protect equipment from sudden fluctuations in current. These are installed in many different pieces of equipment such as power poles and towers, power transformers, circuit breakers, bus structures and steel superstructures in substations. They are designed so that the line current does not follow the overvoltage current to ground. These are used for protecting wireless LAN hardware such as access points, bridges and work group bridges that are attached to a coaxial transmission line. Coaxial lines are susceptible from nearby lightning strikes.

A lightning protection system consists of the following subsystems: air terminals, lightning conductors & down conductors, a grounding electrode, and appropriate bonding. This system is used to protect the buildings from lightning damage. The lightning conductors conduct the lightning current harmlessly to ground and only attract lightning that would have struck the structure anyway.