Third-party inspection services are available through UL, LLC and LPI-Inspection Program and should be part of the building commissioning process.Ī lighting protection system (LPS) requires a network of electrically conductive paths to safely transmit a lightning strike’s 300 million volts from rooftop air terminals-colloquially called lightning rods-to ground electrodes.Īir terminals rise 10 inches or more above a building to intercept lightning before it reaches the structure.
The installer may have to be on the site early in construction to install ground electrodes and bond the LPS to rebar in foundations, and may be one of the last to leave at the end of the project when final connections are made and tested. The specific layout of the LPS can usually be delegated to an LPS installation specialty contractor employing a Master Installer/Designer or Master Installer certified by the Lightning Protection Institute (LPI), see The designer will work with the project team to coordinate locations of and installation schedule for penetrations through the building envelope and connections. If the decision is made to use lightning protection, specify that project comply with NFPA 780, UL 96A - Installation Requirements for Lightning Protection Systems and Lightning Protection Institute (LPI) 175 – Standard for the Design – Installation - Inspection of Lightning Protection Systems. In other cases, the NFPA risk assessment should be conducted by building designers or lightning protection specialists and the results discussed with building owners. Lightning protection is not mandated under the national building codes, but is required in some local codes, by certain government agencies and, by an increasing number of sophisticated building owners. Low risk is not the same as no risk, and designers should conduct a lightning risk assessment for each structure.
Regardless of the outcome of the risk assessment, protection should be given serious consideration if any of the following are factors: Continuity of service requirements and environmental consequences.
Construction Coefficient based on conductivity and combustibility of structure and roofing:.The larger and taller a building, the greater its exposure. Equivalent Collection Area: This is essentially based on the footprint of a building adjusted by the height of the building.While density varies, every state in the Country is at risk. Lightning Flash Density: This is the average cloud to ground lightning flashes per square kilometer per year as based on local meteorological data or the Average US Lightning Flash Density Map from the National Lightning Detection Network.A lightning protection system is recommended if building’s exposure to lightning exceeds tolerable risk as calculated based on following: