Lightning protection is a device or number of devices used to protect a building from lightning strikes. These devices do not prevent lightning strikes, but instead help to minimise damage and injuries. This is primarily done using lightning rods, which offer a "path of least resistance" for the lightning to reach the ground. Lightning protection guidelines are developed by the National Fire Protection Association.
Most lightning protection systems consist of three basic elements: air rods, cables and grounding electrodes. An air rod is a metal pole installed at roof level. Lightning is attracted to the pole, where it is transferred along a cable to the ground level, then neutralised by the grounding electrodes. In commercial structures or buildings full of specialised equipment, surge protectors are used to minimise electrical surges during a lightning strike. Those surge-protecting systems are connected to the building's main electrical service and can prevent damage to equipment by regulating the flow of electricity.
While the National Fire Protection Association's Standard 780 provides guidelines for lightning protection installation, this standard is not considered a law in itself. Many local governments have adapted this standard into their building codes, however, so it can be considered a legal requirement in those specific areas.
Lightning protection is not required on all buildings. Generally the architect and engineers involved in the project will make the determination whether lightning protection is required by local building codes. In some instances, this decision is made by the city fire marshal or other regulatory authority. While most residential buildings are not required to have lightning protection, it is almost always required for high-rises, electrical plants and other buildings that are susceptible to lightning strikes.
In areas where lightning protection is not required, many builders and homeowners may decide to add some type of protection voluntarily. This can help reduce the likelihood of fire or lightning damage, which can protect assets and improve safety. Lightning protection systems can help prevent power outages or damage to municipal electric systems. In instances where lightning protection is added voluntarily, it is usually subject to local building codes that dictate installation standards and material selections.