Lightning Protection Systems (LPS) are often misunderstood by many building owners, architects and engineers. A LPS, when properly designed and installed, provides for a safe, path to earth in the event the structure experiences a lightning strike. The typical system of air terminals (aka “lightning rods”), roof and down conductors, and a below-ground system of rods and conductors creates a dedicated low-impedance path to carry the lightning energy to ground.
Without such a system, that same energy would seek the easiest path through the building and its systems, traveling through steel columns, plumbing risers, electrical conduits, etc. Every metallic building component becomes a potential path. With this unknown path comes the risk of shock to occupants and fire due to arcing as the current jumps from one metal body to another. The purpose of the LPS is to provide an easier path to earth and eliminate or reduce these dangers.
Lightning Protection Systems are not a Code required or mandated system for most construction. NFPA 780 “Standard for Installation of Lightning Protection Systems” provides a risk assessment calculation for any building to help designers and building owners of their relative risk. NFPA does not mandate, recommend or exclude any buildings from having a LPS. Installation of a LPS is an owner and economic choice to be decided during design. Buildings which have a LPS often qualify for lower fire insurance rates. Although not required, many systems undergo a more rigorous inspection and certification process by Underwriters Laboratory which can provide a UL “Master Label” rating.
Installation of a LPS, however, is not a magic bullet for all situations. A LPS is designed to protect the structure from fire due to lightning strikes. Having a system does not guarantee that equipment and systems will not be damaged from the lightning strike. Rooftop mechanical units, electrical equipment, antennae, etc. will most likely be damaged, often beyond repair, if subjected to lightning. Sensitive building electronics including servers, computers, phone systems, electronic lighting ballasts, LED lights, DDC controls, etc. can all be damaged even if far from the actual strike location simply due to voltage increases on the wiring. For this reason, surge protective devices are often installed throughout the electrical system to mitigate this danger.
Despite the myths and misunderstanding which often surrounds a LPS, this is still a relatively low cost protection system to be considered on any project. It requires little maintenance over its long life and has proven its worth on many buildings unlucky enough to experience a direct lightning strike.