Step 1
Evaluate your risk
Reduce the risk of lightn…Thunderstorms occur virtually everywhere and that puts any building at risk. State-of-the-art certified lightning protection systems are a part of the electrical system design of thousands of commercial and public facilities worldwide and are designed to maximize protection of life and property. Risk factors including your location, frequency of lightning and thunderstorms, soil composition and building occupancy determine the need for a lightning protection system.
IBHS recommends that buildings in areas subject to an average flash density of 2 to 3 fl/sq km/yr or greater as defined in the Figure shown below, should have a lightning protection system installed.
Step 2
Finding a solution
Lightning protection systems are designed to protect a structure and provide a specified path to harness and safely ground the super-charged current of the lightning bolt. The system neither attracts nor repels a strike, but receives the stroke and routes it harmlessly into the earth, thus discharging the dangerous electrical event. Investment in a lightning protection system will protect your organization’s investment in its property and equipment.
- If lightning protection systems are to be installed for the building(s) or structure(s), it should be designed and installed in accordance with:
- National Fire Protection Assoc. (NFPA) 780, Standard for the Installation of Lightning Protection Systems
- Underwriters’ Laboratories, Inc. (UL) Standard 96A, Installation Requirements for Lightning Protection Systems
- Lightning Protection Institute (LPI) Standard 175, Standard of Practice for the Design
- Installation
- Inspection of Lightning Protection Systems
- All materials should comply in weight, size, and composition with the requirements of the UL 96 Materials Standards.
- All equipment should be UL listed and properly labeled.
- Equipment should be the manufacturer’s latest approved design of construction to suit the application where it is to be used in accordance with accepted industry standards and with NFPA, LPI, & UL requirements.
- For more information on lightning protection systems, see FM Global Property Loss Prevention Data Sheet 5-11 -Lightning and Surge Protection for Electrical Systems, available through their website: http://fmglobal.com
- Standards and References for Lightning and Surge Protection
- Underwriters Laboratory 96A Standard For Safety-Installation Requirements for Lightning Protection Systems
- Underwriters Laboratory 452 Standard for Safety
- Antenna Discharge Units
- Underwriters Laboratory 497A Standard for Safety-Secondary Protectors for Communication Circuits
- Underwriters Laboratory 498 Standard for Safety-Receptacle and Receptacle Plugs (Including Direct Plug-In Devices)
- Underwriters Laboratory 544 Standard for Safety-Medical and Dental Equipment
- Underwriters Laboratory 1283 Standard for Safety-Electromagnetic Interference Filters
- Underwriters Laboratory 1363 Standard for Safety-Temporary Power Taps (Power Strips)
- Underwriters Laboratory 1449 Standard for Safety-Transient Voltage Surge Suppressors
- National Fire Protection Association 70 National Electric Code
- National Fire Protection Association 780 Standard for the Installation of Lightning Protection Systems
- Lightning Protection Institute (LPI) Standard 175, Standard of Practice for the Design
- Installation
- Inspection of Lightning Protection Systems
- FM Global Property Loss Prevention Data Sheets
- Electrical Section
- Institute of Electrical and Electronic Engineers
- C62 Collection of Guides and Standards for Surge Protection
- Institute of Electrical and Electronic Engineers
- C62.41 Guide for Surge Voltages in Low Voltage AC Power Circuits
- Institute of Electrical and Electronic Engineers
- C62.45 Guide on Surge Testing for Equipment Connected To Low Voltage AC Power Circuits
- Institute of Electrical and Electronic Engineers (std 1100) Emerald Book
- Institute of Electrical and Electronic Engineers Emerald Book (std 1100) FIPS 94
- Institute of Electrical and Electronic Engineers C62.41 Manufacturers (Allan Bradley, Motorola, other suppliers)
- National Electrical Manufactures Association LS-1 Low Voltage Surge Protective Devices
- National Electrical Manufactures Association LS-1
Step 3
Adequate anchorage is important
It is important to make sure that the exposed elements of a lightning protection system are adequately anchored to the structure. In the aftermath of a high wind event, it is not unusual to find that cables and components of lightning protection systems have broken loose from their anchorage points. The movement and impact of the lightning protection components, especially on membrane roofs, can lead to holes and cuts in the roof surface that lead to water intrusion. While it is difficult to estimate the actual loads on the cables when they begin to move in strong winds, it is clear that installations with cables held in place with aluminum prongs on cleats are frequently inadequate in strong winds. Closed loop connectors are better suited for high wind regions. For additional guidance for lighting protection system securement see FEMA publication 549 – Rooftop Attachment of Lightning Protection Systems in High-Wind Regions.
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