Cable and Accessories
Lightning arrestor

A lightning arrestor is designed to protect WLAN devices from static electricity and lightning surges. It is similar in function to a safety valve on a steam boiler. A lightning arrestor prevents energy surges from reaching the equipment by shunting the current to the ground. A lightning arrestor is shown in Figures and .

A lightning arrestor has two main purposes:

  1. To bleed off any high static charges that collect on the antenna, which helps prevent the antenna from attracting a lightning hit
  2. To lessen or dissipate any energy that gets induced into the antenna or coax, which comes from a near lightning strike

The most important part of installing a lightning arrestor is to install a proper earth ground, which will dissipate excess energy. This is typically done using a grounding rod. A grounding rod is a metal shaft driven into the ground, usually to a depth of at least 2.44 m (8 ft). Grounding rods can be made of iron or non-iron materials. When a grounding rod is made of iron or steel, which are ferrous materials, it needs to be at least 15.9 mm (0.63 in.) thick. Non-ferrous rods must be free of all non-conductive materials including paint. It must be greater than 12.7 mm (0.5 in.) thick.

Electricity will follow the path with the least resistance to get to the ground. Most codes call for a ground system of 25 ohms or less. A clamp type meter can be used to measure the resistance of grounding rods. If a single electrode does not meet the grounding requirements, additional electrodes can be added. If multiple electrodes are installed to meet these requirements, they should be at least 1.83 m (6 ft) apart.