Designs for Hidden Lightning Protection Systems
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Designs for hidden lightning protection systems:
This article series describes common lightning protection systems, certification, installation, and lightning protection system inspection. We provide information about lightning strikes, lightning hazards, related equipment, sources of lightning protection system installers, and lightning strike risk assessment
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Design Details for Hidden Lightning Protection Systems Using Copper Components
Example Hidden Lightning Protection System Installation Details
The church tower shown at left, high atop a hilltop in Guanajuato, Mexico, includes both visible and hidden components. The grounding caable is affixed to a corner of the church tower, but near ground level was routed inside of hollowed stone blocks down to its earth connection.
[Click to enlarge any image]
- As with any good construction project, the contract will include a statement that "All equipment shall be installed in a neat workmanlike manner by an experienced installer.
That last part, "experienced installer" is very important in this case since sloppy or improper details can increase rather than reduce the hazards of lightning damage. - All lightning protection system cables shall be concealed within the building, running along the ridge board, down rafters, down wall studs,
and shall exit the building as close to the ground as possible.
If construction is incomplete and a chimney has not been extended above the roof line at the time of installation of the lightning protection system, the lightning protection system cables can be concealed within the masonry. - All components and work shall meet or exceed all national safety and electrical codes including the Lightning Protection Institute (LPI) and the National Fire Protection Association (NFPA), and all components used shall be approved and listed for that purpose by the Underwriters Laboratories (UL).
- The source of all materials is usually listed in order to assure that they are accountable and code-compliant. These lightning protection system specifications and details were provided to us during presentations on lightning protection systems provided to NY ASHI home inspectors and conducted by Associated Lightning Rod Co..
Example Hidden Lighting Protection System Materials
- Building chimneys shall be protected with an air terminal to be placed no more than 2' from any outside corner.
- Lightning protection system air terminals shall be solid copper, round, pointed, 3/8" or larger in diameter, project at least 10" above the object or building section to be protected, and shall comply with UL and LPI requirements for lightning protection systems and shall be located within 2' of outside corners and at intervals no greater than 20 horizontal feet (along the ridge line).
- Air terminal bases shall be made of cast bronze and shall be securely mounted using pressure-bolt or crimp connectors and stainless steel screws, nails, or bolts.
- Lightning Protection System Cabling shall all be 28-strand 16 gauge copper (230#/1000', 72,258 mils or equivalent).
- Corrosion protection shall be provided by lead coating on metal components (air terminals, terminal bases, cable connectors, strapping,) where located within 2' of the chimney top.
- Cable fasteners shall be made of 1/2" wide 20 ga. copper strips and shall be spaced at 2' intervals (exceeding the UL and LPI requirements).
- Ground rods shall be at least 1/2" in diameter and 11' long, and driven into the ground 10', leaving 1' of the ground rod exposed [this is the UL standard] and shall be connected to the lightning protection system by two-bolt cast-bronze clamps at least 1.5" long and using stainless steel cap screws. UL requires that at least two ground rods shall be installed.
- Metal components on the building such as antennas, weather vanes, and metal gutters are connected to the roof or down conductor
- Building ground-devices such as water piping, electrical systems, telephone, cable, internet systems, and metal waste piping shall be grounded in common and bonded to the lightning protection system using full-sized grounding conductors.
- Other hardware such as miscellaneous bolts, nuts, nails, screws, shall be stainless steel.
- Surge protection devices are installed at receptacles on for circuits serving electronic equipment like computers, TV's, or other electronics. Surge protection may also be installed at the electrical panel to protect the circuit serving a well or well pump, or to protect equipment from strikes drawn to steel well casings protruding above ground as well as to protect building appliances.
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Citations & References
In addition to any citations in the article above, a full list is available on request.
- Portions of this information are based on UL publication 200-81 11/87 and other local service company information about lightning protection systems and lightning strike hazards.
- Special thanks to Associated Lightning Rod Company, Cooper Road Box 329A, Millerton NY who has been contributing technical content in presentations to NY ASHI home inspectors since 1996. Some of that information [on lightning system material and installation details] was edited for clarity. ALRCi can be reached at 518-789-4603, 845-373-8309, 860-364-1498 and will inspect your lightning protection system at no charge. [We have no financial nor any other business relationship with any company or product discussed at this website--DF]
- For more details on how lightning protection systems work, see Lightning Protection from Pacific Electric and Gas Company, and Electrical System Grounding and Lightning Protection, Engineering Technical Letter 90-6, Department of the Air Force, HQ USAF.
- Lightning strike risk assessment: for the full body of this excellent article which summarizes recent opinions about lightning strike risk assessment and safe practices for individuals or groups needing to avoid being struck by lightning, see Updated Recommendations for Lightning Safety - 1998 Ronald L. Holle and Raul E. Lopez from National Severe Storms Laboratory, NOAA and Norman, Oklahoma, Christoph Zimmermann Global Atmospherics, Inc. Tucson, Arizona
- As we indicated in an original version of this article, a lightning strike risk assessment guide can be found in Appendix I of the National Fire Protection Association's Lightning Protection Code, NFPA #780. The guide considers type of structure, type of construction, structure location, topography, occupancy, contents and lightning frequency. Contact NFPA, Batterymarch Park, Quincy, MA 02269 617-770-3000.
- Lightning Protection Institute, 3365 N. Arlington Heights Rd., Suite J., Arlington Heights IL 60004
- Underwriters Laboratory Standard UL96A. These requirements cover the installation of lightning protection systems on all types of structures other than structures used for the production, handling, or storage of ammunition, explosives, flammable liquids or gases, and other explosive ingredients including dust. These requirements apply to lightning protection systems that are complete and cover all parts of a structure. Partial systems are not covered by this standard. These requirements do not cover the installation of lightning protection systems for electrical generating, distribution, or transmission systems. These requirements do not cover lightning protection components, which are covered by the Standard for Lightning Protection Components, UL 96.
- Underwriters Laboratory Standard UL96: These requirements cover lightning protection components for use in the installation of complete systems of lightning protection on buildings and structures. These requirements do not cover the installation of lightning protection components. Products of this type are covered by the Standard for Installation Requirements for Lightning Protection Systems, UL 96A.
- "Lightning Awareness," Gerry Schulte, BMW ON magazine, June 2007 pp. 58-60, provided some technical details about lightning, and refers readers to www.lightningsafety.noaa.gov/outdoors.htm
- Our recommended books about building & mechanical systems design, inspection, problem diagnosis, and repair, and about indoor environment and IAQ testing, diagnosis, and cleanup are at the InspectAPedia Bookstore. Also see our Book Reviews - InspectAPedia.
- Armor Lightning Protection Inc Manchester Center, VT, 802-375-0266 state-of-the-art lightning protection and surge protection for residential and commercial buildings in Vermont, New England, and throughout the Northeast
- Associated Lightning Rod Company, Inc., Box 329A, Cooper Road, Millerton, NY 12546 914/373-8309 518/789-4603
- A-C Lightning Security, Inc., 2100 East First St., PO Box 329, Maryville MO 64468 816-582-8115 800-821-5575 816-562-2932. In New York, Hudson Valley, contact Christensen Electrical Power Systems, Richard G. Christensen, 518-537-4128.
- Lightning Eliminators & Consultants6687 Arapahoe Road Boulder, CO 80303 (303) 447-2828. "Engineering Solutions For Lightning, Grounding and Surge Protection Worldwide Since 1971"
- Electrical EINET
- Lightning Protection for Facilities, Dr. Bruce Gabrielson, Robert B. Marcus, Published and presented: EMCEXPO92, Washington D.C.
- MIT's Electrical Safety Files
- Lightning Protection for Workers What to Do if You're Outside in a Lightning Storm - Center to Protect Workers' Rights (PDF)
- 1998 and Current Lightning Protection Conferences & Exhibitions
- Lightning Risk and Hazard Analysis Measurement from the National Lightning Safety Institute (NLSI).
- "Lightning Fatalities, Injuries, and Damage Reports in the United States from 1959-1994", E. Brian Curran, Ronald L. Holle, Raul E. Lopez, NOAA Technical Memorandum NWS SR-193 October 1997
- UL - Underwriters Labs Lightning equipment certification program. "Underwriters Laboratories Inc. (UL) has been testing and certifying lightning protection equipment since 1908. UL issues certificates of conformance for systems, inspecting system components and checking completed installations. Installations are required to comply with UL's internationally recognized Standards for lightning protection systems. Manufacturers, suppliers and installers demonstrate their commitment to safety by building, selling and installing only those lightning protection products that pass UL's rigorous testing." -- (Op.Cit.)
- * Safety Hazards and Safe Inspection Procedures for Electrical and Home Inspectors at Residential Electric Panels
- Aluminum Wiring Information WebsiteAluminum Electrical Wiring Hazards and Repairs: in-depth authoritative info, photos, documents including selection of proper vs. ineffective repair methods. E.g.: Ideal 65 "Twister" purple connector fails in field and lab testing with aluminum wire.
- Electrical Panels, How to Inspect in buildings, safety for electrical inspectors, electrical panel, fusing, wiring defects, defective products. Inspection Class Presentation
- Lightning Strike Risk Assessment, Protection Systems & Services
- Multi-wire branch circuit inspection and defects
- Rust and Corrosion in Electrical Panels, A Study and Report on Frequency and Cause for Electrical and Home Inspectors at Residential Electric Panels
- Directory of Home Inspectors accessible via internet
- Electrical System & Wiring Hazard Inspection, Detection, Cause, Remedy, Prevention - Main Electrical Page
- In addition to citations & references found in this article, see the research citations given at the end of the related articles found at our suggested
CONTINUE READING or RECOMMENDED ARTICLES.
- Carson, Dunlop & Associates Ltd., 120 Carlton Street Suite 407, Toronto ON M5A 4K2. Tel: (416) 964-9415 1-800-268-7070 Email: info@carsondunlop.com. Alan Carson is a past president of ASHI, the American Society of Home Inspectors.
Thanks to Alan Carson and Bob Dunlop, for permission for InspectAPedia to use text excerpts from The HOME REFERENCE BOOK - the Encyclopedia of Homes and to use illustrations from The ILLUSTRATED HOME .
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