Lightning protection is an integrated system of air terminals, down conductors, and earth electrodes that intercepts a lightning strike and channels its energy harmlessly into the ground, preventing structural damage, fire, and harm to occupants.
How it works
The principle
A lightning protection system (LPS) does not prevent lightning from striking a building. Instead, it provides a low-resistance path that attracts the discharge and conducts the enormous current — often exceeding 100,000 amperes — safely to earth before it can pass through the building structure, wiring, or flammable materials.
Main components
- Air termination network — copper or aluminium rods (also called lightning rods or Franklin rods) and horizontal conductors mounted on the roof ridge, parapets, and any elevated features such as chimneys or antennas.
- Down conductors — metal strips or cables that run vertically down the exterior of the building, connecting the air termination network to the earthing system. They are spaced at regular intervals around the perimeter.
- Earth termination (grounding) — copper-clad rods driven deep into the ground, or a ring conductor buried around the foundation, designed to dissipate the current into the soil.
- Bonding — all major metallic elements within and on the building (steel frame, reinforcement, pipes, cable trays) are bonded to the LPS to prevent dangerous voltage differences during a strike.
Standards and risk assessment
Design of a lightning protection system follows standards such as IEC 62305 (international) or NEN 1014 (Netherlands). A risk assessment determines the required protection level based on building height, location, use, and the consequences of a strike. Tall buildings, hospitals, data centres, and structures containing flammable or explosive materials typically require the highest level of protection.
Maintenance
An LPS must be inspected periodically — usually every one to four years — to check for corroded connections, damaged conductors, and changes to the building that may leave new features unprotected.
Related terms
- Earthing (grounding)
- Surge protection
- Equipotential bonding
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