NFPA 780-2020 Standard for the Installation of Lightning Protection Systems

NFPA 780-2020 Standard for the Installation of Lightning Protection Systems. 8.1.3 Where the following conditions are niet, lightning protection sstenis shall be permitted to be omitted: (1 ) The facility is sen’ed by an approved local lightning warning sstem as determined by the AHJ. and the lightning wanting system permits explosives operations to be termni— nated before an approaching thunderstorm is within 10 mi (16 kin) of the installation. (2) All personnel are evacuated to a shelter pmovmcling adequate protection. (3)* The resulting damage and loss from a lightning strike are are eptal)le to the Al lJ (4) The facility contains only explosive materials that cannot be initiated by lightning, and where no lire hazard exists, as deterunmied in’ clocmnentnl tests amid analyses and approved by the AHJ. (5) Personnel are not expected to sustain injttn’: there will be a mniiiiiiial ecoiloitlic h)s.5 to time structure, its eontetits, or the surrounding facilities: and the resulting damage and loss from a lightning strike are acceptable to the AHJ. 8.1.4 For tltc&se locations where no strike tenninatunis are installed, bonding, grounding, and SPDs shall be installed as described in Sections ‘1.20,8.5, and 87. 8.2 General. 8.2.1 Striking Distance. Lightning protection systems designed to protect structures housing explosives shall be based on a striking distance of 11)0 ft (30 m), as disrtmssed in 4.8.3,1.1. 8.2.2 Electromagnetic Coupling. Where the ellécts of electromagnetic cotiphng are ol concern, a mast or overhead wire (catenary) system shall be installed. 8.3 T’pes of Lightning Protection. 8.3,1 General. Except as excluded by 8.1.3, structures containing explosives shall have lightning protection consisting of one or more ol the types gisen in 8.3.2 through 8.3.5. 8.3,2* Metallic (Faraday-Like) Cage. %there optimum protecnon for structures housing explosives is required (as determined by the Al iJ), a grounded. continuotisly conductive enclostire, as shown in Figure 8.3.2, shall he used. 8.3.3 Single or Multiple Masts. Mast-type systems shall be desigiwd as specified iii ‘1.6.3 and ‘1.6.5, tising a striking distance as specified in 8.2.1. 8.3.3.1 Nonmetallic masts shall have a strike termination device or metal cap with a tuinitutmni thickness of ‘s in. (‘1.8 mm) connected to ground hs at least one down conductor. 8.3,3.2k Mast guy wires shall not he used as the only down conductors for a mast. 8.3.3.3 Each metallic guy cable shall be interconnected at its lower end to the grounding electrode(s) for the down conductor. 8.3.3.4 Metallic guy...