The three parts of a lightning protection system
Lightning protection systems are designed to create a path for huge currents to pass safely away from a property, rather than striking it directly. If a structure doesn’t have a system in place, the current could flow into all kinds of conductors including phone lines, cabling or metallic utility pipes as it seeks a route to the ground. Steel framed buildings are at increased risk because the current could flow through the structure itself.
Having a protection system in place will not prevent lightning from striking a property, as this is physically impossible. The only way to protect the structure is to create a system to redirect the current as safely as possible and reduce the possibility that it will take different paths to ground.
Air terminals (lightning rods) need to be positioned on specific parts of the roof, particularly on the highest points such as the chimney and the ridge. They come in many different forms but are usually made from highly conductive metal. They can be topped with a tall, needle point or a smooth, highly polished sphere.
The terminals will connect to conductor cables that run along the top and edges of the roof. These will then extend down the side of the property to the ground. This creates a very easy path free from obstacles for current to flow through.
Once they reach ground, the conductor cables will be connected to grounding rods. Each rod is a long sturdy piece of metal that is driven deep into the earth. This means that when electricity flows down the cables it will dissipate harmlessly into the ground. The rods need to be buried deep enough to ensure that the current won’t reach buried cables and utilities.
Lightning protection systems don’t necessarily need to have air terminals to function. The idea is that current is more likely to strike the highest point. By having rods extending up from the property, you have greater control over where the current will go if lightning does occur. If you have good cable coverage and grounding you may not need to install terminals.