A well-installed and maintained lightning protection system routes lightning along a known, controlled course between the air and moist earth with over 90 percent effectiveness in preventing damage. Such systems can prevent damage to a building or any loss of income related to this damage. Air terminals are rods or tubes of metal that are installed at every projecting high point of a building, such as roof peaks, chimneys, dormers, ventilators, gables, flagpoles, towers and water tanks. To be effective they must not be spaced too widely apart. Conductors connect air terminals with grounds.
Conductors are copper or aluminum cables.
Grounds and ground connections provide contact with the earth for dissipation of the lightning charge. Usually, at least two ground connections are needed for any building-more with large or complex structures. They should be apart from building foundations and extend deeply enough to reach moist subsurface earth no matter how dry the weather. Bonding is the interconnecting of metal parts to prevent sideflash. Lightning arrestors guard against damage that might occur by way of the electric power lines.