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 SystemA LPS requires a network of elec-trically conductive paths to safely transmitalightningstrikes300 million volts from rooftop air termi-nalscolloquially called lightningA lightning protection system creates a conductive path to channel lightning into the ground without rodsto ground electrodes.damaging the building and its occupants and contents. Components must be UL-listed for lightning Air terminals rise 10 inches orAD HEREprotection; products listed for electrical power systems are not up to the challenge of lightnings extreme more above a building to interceptcurrent. Illustration courtesy of East Coast Lightning Equipment Inc.lightningbeforeitreachesthe structure. Lightning is modeled as a 300-foot diameterrequired on rooftop of equipment that is not within the sphere being rolled over a buildings envelope; anywherezone of protection of an air terminal mounted higher on the the sphere touches the building is susceptible to becomingstructure. The rolling sphere technique is demonstrated in lightnings attachment point. Based on this, NFPA 780an animation at bit.ly/rolling-sphere.requiresairterminalsatroofcornersandatintervalsIn most buildings, lightnings energy is conveyed from not exceeding 20 feet along roof ridges and edges; a veryair terminals to the ground through large, multi-strand wide roof requires additional air terminals 50 feet-on- cables made from highly conductive grades of aluminum center through the field of the roof. Air terminals are alsoor copper; copper should not be used in contact withThe air terminals on this ridge are supported from below the roof deck and Air terminals must be installed on rooftop equipment that is not within the zonesealed against weather intrusion. They are connected to each other and to of protection created by air terminals mounted at a higher elevation on theground by conductor cables inside the attic to maintain the design standards of building. Photo courtesy of Labeled Lightning Protection Inc. this luxury resort development. Photo courtesy of Mr. Lightning.30 www.mrca.orgMidwest RooferBE_Winter18_MetalRoofingFeature.indd 28 1/17/18 11:46 AM'