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What is a Lightning Protection System?

Christina Edwards
Christina Edwards

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.

A water tower with a lightning protection system.
A water tower with a lightning protection system.

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.

Lightning.
Lightning.

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.

Lightning striking a field.
Lightning striking a field.

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.

Discussion Comments

Feryll

When I was a kid we would have big thunder and lightning storms during the summer--almost every afternoon or evening. One summer lightning struck the house and ran in and knocked out our TV. The TV was fried and we had to get another one.

About a week later, another thunderstorm struck and sure enough lightning hit the house again and knocked out the new TV. Who said lightning doesn't strike twice? Anyway, dad figured out that the lightning had hit a tree branch and then ran into the house. He cut the branch.

The one lesson I learned from that experience is to always use surge protection. It's much less expensive to buy a few surge protectors than it is to buy a new TV or computer.

Drentel

@Animandel - Benjamin Franklin figured it all out over two hundred years ago. If you place a lightning rod higher than the building it is set up to protect then it will pull the energy that's above the house. It is not going to attract lightning that is 100 yards away or any considerable distance.

The lightning that the lightning rod attracts is energy that is above the house and would have most likely hit the house had it not been pulled in by the lightning rod first.

Animandel

I don't fully understand how lightning rods work. I understand the part of the article where it talks about how the lightning rods absorb the lightning and take it to the ground so that it will not destroy the building it is attached to. But, since the rods attract bolts of lightning, don't they put buildings in greater danger? Or at least, don't they bring more lightning to the area around the building?

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    • A water tower with a lightning protection system.
      By: chandelle
      A water tower with a lightning protection system.
    • Lightning.
      By: mackflix
      Lightning.
    • Lightning striking a field.
      By: Leonid
      Lightning striking a field.
    • A lightning rod can help protect a building from lightning strikes.
      By: Ansebach
      A lightning rod can help protect a building from lightning strikes.