b'Steep Slopeand installation schedule for pen-etrationsthroughthebuilding envelopeandconnections.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.Third-party inspection services areavailablethroughUL,LLC and LPI-Inspection Program and shouldbepartofthebuilding commissioning process. It Takes a System Air terminals must be located at high points and where indicated by NFPA 780. Conductor cables that are exposed to view should be installed along the natural lines of a building to minimize their visual impact. A LPS requires a network of elec- Photo courtesy of Guardian Equipment Company. COVID-19 trically conductive paths to safely transmitalightningstrikes300galvanized steel, aluminum, or most other non-cupreous metal roofing or siding. TheINFORMATION million volts from rooftop air termi-cables must interconnect air terminals and bond to metal elements on the roof. nalscolloquially called lightningA lightning protection system creates a conductive path to channel lightning into the ground withoutA wide variety of air terminal bases and cable fasteners are available for installingFOR ROOFING rodsto ground electrodes.damaging the building and its occupants and contents. Components must be UL-listed for lightning Air terminals rise 10 inches orprotection; products listed for electrical power systems are not up to the challenge of lightnings extremeLPS components on metal roofs. Screw-installed devices can sometimes be used onCONTRACTORSmore above a building to interceptcurrent. Illustration courtesy of East Coast Lightning Equipment Inc. ridge caps, and adhesively-mounted devices areAD HERE holes available that avoid drilling lightningbeforeitreachesthethrough the roof. On better-quality buildings and in high wind areas, devices that structure. Lightning is modeled as a 300-foot diameterrequired on rooftop of equipment that is not within theclamp onto a roofs standing seams should be considered. Ideally, the LPS is installedMRCArecognizesthis sphere being rolled over a buildings envelope; anywherezone of protection of an air terminal mounted higher on theduring construction, with all conductorsis a time of uncertainty, the sphere touches the building is susceptible to becomingstructure. The rolling sphere technique is demonstrated ininstalled below the roof deck, so just the lightnings attachment point. Based on this, NFPA 780an animation at bit.ly/rolling-sphere. air terminals are exposed above the roof.and we want to be your requiresairterminalsatroofcornersandatintervalsIn most buildings, lightnings energy is conveyed fromFrom the roof, NFPA requires pathsresource for addressing not exceeding 20 feet along roof ridges and edges; a veryair terminals to the ground through large, multi-strandtoground.Downconductorcables wide roof requires additional air terminals 50 feet-on- cables made from highly conductive grades of aluminumfrom roof to grade can be left exposedvarious issues you may center through the field of the roof. Air terminals are alsoor copper; copper should not be used in contact with to minimize penetrations through thebefacinginmanaging building envelope. The visual impact of exposed cables can be reduced by locatingyourbusinessthrough downconductorsawayfrommainthecrisis.Findup-to-entrances, behind downspouts, and along a buildings edges or other architecturaldate information atlines. Large radii are required wherever a cable bends, including at the junction ofwww.mrca.org a roof and wall.Alternatively, through-structure pen-etrationdevicescanbeusedtobring conductorsintothebuildinginterior; conventionalflashingscanbeusedto seal the penetrations. This reduces the visibility of conductors on the exterior of the building and helps protect them from damage and theft. More, this can reduce costs by allowing a buildings structural The air terminals on this ridge are supported from below the roof deck andAir terminals are installed on parapets, the higheststeel framing (if present) to be used as Air terminals must be installed on rooftop equipment that is not within the zonesealed against weather intrusion. They are connected to each other and tolocations on this roof. Flexible boot flashings aredownconductors.NFPAstates:The of protection created by air terminals mounted at a higher elevation on theground by conductor cables inside the attic to maintain the design standards ofused to seal the through roof penetrations.building. Photo courtesy of Labeled Lightning Protection Inc. this luxury resort development. Photo courtesy of Mr. Lightning. Photo courtesy of Mr. Lightning. metal framework of a structure shall be per-mitted to be utilized as the main conductor www.mrca.orgMidwest Roofer 312.25x9.875.indd 2 8/23/17 3:34 PMBE_Winter18_MetalRoofingFeature.indd 28 1/17/18 11:46 AM BE_Winter18_MetalRoofingFeature.indd 29 1/19/18 11:35 AM'