Lightning protection systems are designed to protect large structures from damage from lightening. These systems allow lightning strikes to travel safely from the top of a structure to the ground, often causing little or no damage. Main components of a lightning protection system include lightning rods, down conductors, and electrodes buried in the ground. A building that is not protected with a lightning protection system could suffer severe damage, and there is also a possibility of injury to the occupants.
In basic terms, a lightning protection system offers the lightening an easy path to the ground. Instead of having to go through wood, masonry, or other materials, the system provides a low-resistant, or low-impedance, path to the ground. Each part of a lightening protection system is usually made from metal, typically aluminum or copper.
Lightening rods, or air terminals, are some of the main components of a lightening protection system. These long metal rods are usually set up on top of a structure, at the highest point. Some larger structures may benefit from more than one rod. For example, on buildings lightning rods are typically spaced about 20 feet (6 meters) apart. Therefore, a building that is 80 feet (24.5 meters) long may require three or four rods.
Lightning rods are usually connected to other metal components on top of a structure, such as a television antenna. They are also connected to down conductors. These metal cables or wires connect the lightning rods to an underground metal rod.
Earth electrodes are the final component of a lightning protection system. These metal rods are buried in the ground, often at depths of 10 feet (3 meters) or more. Here, the high voltage of the lightning strike can be distributed safely in the ground. Sometimes, these electrodes can be buried surrounded by salt, which can enhance the electrical connection to the surrounding earth.
The wiring and electrical systems of a building are also subject to damage after a lightning strike. Surge protectors, which can protect these systems, are another component of a lightning protection system. These work by limiting the excessive rise in voltage.
A lightning protection system can be installed on any number of structures, including buildings, trees, water towers, monuments, and bridges. Wooden structures that are not protected by these systems are at risk of catching on fire and burning. Porous or water-laden building materials, like brick and concrete, can even explode if struck by lightning.