Lightning Protection System (LPS)

Lightning Protection System (LPS): a short overview A lightning protection system is designed to protect buildings, people, and equipment from direct and indirect lightning strikes. Its goal is to provide a low-impedance, safe path for the lightning current to follow from the point of strike to the earth, while minimizing the risk of fire, electrical surges, and collateral damage. How an LPS works - The air termination (the “air terminals” or lightning rods) intercepts a direct strike. - Conductors carry the lightning current away from the building. - An earth termination network (grounding electrodes) distributes the current into the earth with low impedance. - Equi-potential bonding connects structural metalwork, electrical installations, and communication systems to reduce dangerous potential differences. - Surge protection devices (SPDs) at service entrances and on sensitive circuits help limit overvoltages from indirect effects of a strike (transients). Key components and concepts - External LPS: air terminals, down conductors, and an earth termination system. This part protects the building envelope from direct strikes. - Internal LPS (where used): bonding of metalwork inside the building and acceptance of transient overvoltages through SPDs to protect electrical and data systems. - Earthing/grounding: a low-resistance path to the earth is essential for the system to work effectively. - Bonding/Equi-potential bonding: ties together various conductive parts to avoid dangerous voltage differences during a strike. - Protection levels and zoning: LPS designs often reference protection levels or Lightning Protection Zones to determine how many air terminals and conductors are needed and where they should be placed. Standards and design approach - Design and installation should follow recognized standards and local codes. Common references include IEC 62305 (general principles, risk management, and system design) and national adaptations; NFPA 780 is widely used in some regions. - Typical design steps: - Conduct a risk assessment of the structure and contents (occupancy, use, and critical systems). - Define protection goals and zones (for example, higher protection near critical equipment or people). - Select appropriate protection levels and determine the layout of air terminals, conductors, and the earth network. - Plan integration with other building systems and ensure compatibility with SPDs and bonding. - Install and verify with testing and commissioning. Maintenance and inspection - An LPS requires periodic inspection to verify that conductors are intact, connections are secure, and the earth resistance is within required limits. - Damaged or corroded components should be repaired or replaced promptly. - SPDs should be tested or replaced according to the manufacturer’s recommendations and local codes. What the LPS can and cannot do - It reduces the risk of damage from direct strikes and mitigates indirect effects by providing a safe current path and reducing voltage differences. - It does not guarantee that a strike will not occur or that all damage will be prevented. Proper maintenance and integration with other protective measures (such as proper building design and surge protection) are essential. Who should install an LPS - A licensed lightning protection contractor or electrical contractor with experience in LPS design and installation should perform design, installation, and testing. - Local codes, site conditions, and building use all affect the final design. In brief, a well-planned LPS lowers the risk of fire and equipment damage from lightning by safely directing the surge to the ground and ensuring all conductive parts in and around the building are properly bonded and protected.