Lightning strike or bolt damage protection systems.

This lightning protection system website 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.

The lightning bolt photograph at page top was taken by the author from an aircraft.

What is Lightning, What makes lightning strike? Which way does lightning move?

Example of lightning-related damage to a home: This house fire in Georgia was caused by a lightning strike in April, 2008.

According to UL, "lightning is the visible discharge of static electricity within a cloud, between clouds, or between the earth and a cloud". Thunderstorms occur when warm and cold air masses meet.

[Click to enlarge any image]

Charges of electrical energy build up within the air masses and periodically discharge as energy flows from one area to another.

Upwards-moving air in the churning caused where the cold and warm fronts meet causes a separation and movement of positively-charged ions or particles to the top of clouds, leaving negative charges at the bottom of clouds.

Lightning bolts may pass vertically or horizontally between clouds or may move between the air and the ground where energy is finally dissipated.

As lightning moves towards the earth (in the form of downwards flowing negatively charged electrical energy called a "pilot leader"), positive "lightning bolts" actually move upwards from vertical features on the earth such as the edges of buildings, chimneys or trees, reaching towards along an ionized path in the air towards the downwards-moving negative energy.

It's interesting that UL says the energy moves in discrete 150' steps, ionizing a pathway in the air.

Types of Building Damage Caused by Lightning Strikes

The photo above shows the extent of fire damage to the same house as the fire photo above. Damage to a home subject to a lightning strike and subsequent major fire could be expected to include:

1. Lightning strike damage
   
    to the home - damage caused by the lightning strike itself
2. Fire damage 
   
   to the home, caused by the subsequent fire resulting from the lightning strike
3. Water damage 
   
   to the home, damage to the structure caused by water used to extinguish the fire. In this instance water contacting bricks heated by the fire may have caused additional losses.
4. Mold contamination:
   
   risk of damage to the structure from mold growth resulting from wet conditions in any wall, ceiling, or floor cavities or surfaces which were wet during the extinguishment of the fire, if these areas were not also promptly opened, wet materials removed, and the building dried quickly.
   
   Our photographs of house fires caused by lightning strikes (above) were contributed by website readers.

UL adds that "Scientists still do not fully understand what causes lightning but most experts believe that different kinds of ice interact in a cloud. Updrafts in the cloud separate charges so that positive charges end up at the top of the cloud while negative flow to the bottom."

Our photograph of multiple lightning arrestor masts (left) shows a lightning protection system for an electrical power substation on the Hudson River.

[Our photograph of lightning shown at page top was of strikes moving between high clouds and was taken by the author from an airplane over northern Minnesota.]

When the negative charge moves down, a pilot leader forms. This lightning strike leader rushes toward the earth in 150 discrete steps, ionizing a path in the air. The final breakdown generally occurs to a high object and the major part of the lightning discharge is then carried in the return stroke which flows along the ionized path.

What is the Amount of Energy in Lightning Strikes? What Causes Thunder?

A lightning bolt that strikes the ground, "groundstroke lightning, is producing a tremendous electrical current, around 100,000 amps. (By contrast a typical home electrical panel supports 100 to 200 amps of current to operate everything in the home).

The energy in a 100,000 amp lightning strike can in turn produce very high temperatures, up to 50,000 deg. F (this is five times hotter than the surface of the sun!). It's the rapid heating (expansion) and then cooling (contraction) of air around a lightning strike that produces the shock wave (air movement) which is heard as a thunderclap during lightning storms.

Incidentally, while lightning is normally associated with thunderstorms, lightning strikes can also be caused by erupting volcanoes, hurricanes, forest fires, and (let's hope not) nuclear explosions.

A lightning protection system does not prevent lightning from striking; it provides a means for controlling it and preventing damage by providing a low resistance path for the discharge of lightning energy. [Quotations are from UL publication 200-128C 25M/9/93]

What Are Lightning Protection Systems?

A lightning protection system does not prevent lightning from striking; it provides a means for controlling it and preventing damage by providing a low resistance path for the discharge of lightning energy.

But lightning protection systems have a confusing history

The earliest lightning rod design, by Ben Franklin, ended in a sharp pointed trident which may have actually created an electrical field around the tip which invited strikes.

You'll notice that modern lightning rods have a short blunt tip and that they are connected to earth by heavy metal cables, often using braided copper.

Having a properly-designed lightning protection system is very important if you're going to have one at all, since an improperly designed or installed system might actually increase the chances of a building being damaged by a lightning hit.

Lightning strikes at buildings and other sudden electrical currents (such as a tree touching a high tension power line) produce very high voltages which can take surprising routes at a property such as following underground tree roots, metal porch railings, and copper or steel building water pipes.]

 

How do Lightning Protection Systems Work?

Lightning protection systems control electrical discharges by directing them through a low-resistance path to the ground, avoiding passage through parts of a structure and reducing risk of fire or other damage.

Air terminals (rods - the sketch here is of a rod tip) are fastened to the building to intercept electric discharges which might otherwise strike a building component itself, such as a chimney or metal roof.

Electrical discharges striking the air terminal are directed through heavy duty metal conductors to a grounding system (rods driven into the soil) and thence into the earth.

The lightning protection system was first invented by Ben Franklin in 1752.

 

Example of a Damaged Lightning Protection System

We took these photographs of a damaged lightning protection system on an 1865 house in Orange County, New York.

The air terminal and conductor were bent down away from the top of the home leaving the chimney and roof (a metal one in an area of frequent lightning strikes) unprotected.

This is an example of what can happen when someone who is not qualified works on the system. The lightning protection system for this home was dangerously compromised when the maintenance crew simply bent components down out of their way.

[The photographs of details of an old lightning protection system shown here were NOT the work of any of the companies or sources described at this website.]

Lightning Protection System Research & Guides

For more details on how lightning protection systems work, see

• LIGHTNING PROTECTION [PDF] Pacific Electric and Gas Company, retrieved 2022/10/09, original source: https://www.pge.com/pge_global/common/pdfs/outages/current-outages/report-view-an-electric-outage/additional-resources/Lightning_Protection.pdf
  
• ELECTRICAL SYSTEM GROUNDING AND LIGHTNING PROTECTION [PDF] Engineering Technical Letter 90-6, Department of the Air Force, HQ USAF. - http://www.afcesa.af.mil/userdocuments/publications/ETL/ETL 90-6.pdf
• Fisher, Charles E., LIGHTNING PROTECTION for HISTORIC STRUCTURES [PDF] COMPLETE VERSION (2017) Preservation Brief No. 50, US NPS, US DOE, retrieved 2022/10/09, original source: https://www.nps.gov/tps/how-to-preserve/preservedocs/preservation-briefs/50Preserve-Brief-Lightning-Protection.pdf
  Excerpt:
  This Preservation Brief is designed for owners, property managers, architects, contractors, and others involved in the preservation of historic structures.
  
  It includes information on the care, maintenance, and repair of historic and older lightning protection systems; discusses factors to consider in assessing the need for a lightning protection system where none exists; and includes historic preservation guidance on the design and installation of new systems
• Lightning Protection, SECTION 620 GROUNDING AND LIGHTNING PROTECTION SPECIFICATIONS [PDF] - retrieved 2022/10/09
• 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 - http://www.nssl.noaa.gov/mag/holleetal.html 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
• MI, GROUNDING, BONDING, LIGHTNING PROTECTION AND SURGE PROTECTION FOR ELECTRICAL SYSTEM EQUIPMENT [PDF] Michigan DOT, retrieved 2022/10/09, original source: https://mdotcf.state.mi.us/public/dessssp/spss_source/20SP-826A-01.pdf
• NFPA 780 - Lightning Protection Code
• nVent LIGHTNING PROTECTION SOLUTIONS, NVent Erico Systems, Web: https://www.nvent.com/m retrieved 2022/10/09, original source: https://www.nvent.com/sites/default/files/acquiadam/assets/E1147C-WWEN.pdf
• 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.
• USAF, GROUNDING SYSTEMS, AIR FORCE INSTRUCTION 32-1065 [PDF] (2017) - retrieved 2022/10/09 original source: https://www.wbdg.org/FFC/AF/AFI/afi_32_1065_2017.pdf
  Excerpt:
  This instruction implements Air Force Policy Directive (AFPD) 32-10, Installations and Facilities. It assigns maintenance responsibilities and requirements for electrical grounding systems on Air Force installations, including systems for equipment grounding, lightning protection, and static protection.
• "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
• LIGHTNING PROTECTION FOR WORKERS [PDF] What to Do if You're Outside in a Lightning Storm - Center to Protect Workers' Rights (PDF)

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Reader Q&A - also see RECOMMENDED ARTICLES & FAQs

Reader Question: (July 26, 2012) Deji@Imon wireless said:

Good day to you. Please we are a Vsat solutions provider. and our operations is majorly in a terrain with high Ionic Content which brings us under serious lightning and thunder attacks.

Please, i would greatly appreciate if you could advice us on what to do and if you have products that could help us, we would appreciate if you could avail us the necessary details.

Reply:

Deji, Best would be for you to search InspectApedia for "lightning protection" and you'll find all of our information there.

...

Continue reading at LIGHTNING PROTECTION SYSTEMS, DEFINITIONS or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

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Suggested citation for this web page

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Citations & References

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