Generally, a protection system for buildings must include air terminals, down conductors, secondary conductors, arresters and ground connections, with all system components linked together. How Lightning Behaves Lightning is a visible discharge of static charges that can occur within a cloud, between clouds or between a cloud and the earth. A bolt packs so much voltage that it may leap a mile or more through the air. Lightning strikes buildings or other objects because the materials in them provide easier paths to ground than the air. Lightning is more likely to strike on projecting objects such as tress, poles, wires or building steeples than on larger, flatter surfaces projecting to the same height or lower.
Lone buildings are also primary targets.
When a lightning bolt uses a building or other object as an electrical conductor, it generally follows a metallic path to the ground. Sideflashes are dangerous because they can ignite a fire or cause electrocution. Lightning can enter a building through a direct strike, by striking a metal object attached to the building, by leaping over to the building after striking a nearby tree, or by following a power line or ungrounded wire fence attached to a building. Utility distribution systems use multiple groundings per mile and other protective devices to help dissipate lightning strikes and send them to the earth. More About Fencing Systems You can obtain a copy of the publication Installation and Operation of Fencers, Cow Trainers and Crowd Gates from the Wisconsin Farm Electric Council.