Frequently Asked Questions
Is it unsafe to be out on the water in a speedboat or sailboat?
Lightning pulls ions from objects on the earth to make the connection between clouds and ground that we see as a lightning stroke. Many items because of their shape release ions more easily. This may include pointed items or metal objects that reach into the ground. We normally equate this to lightning striking the tallest, best conductor in the area. The human body is an excellent conductor (this is why you can be shocked by electricity), and normally a better path for a lightning strike to ground than the materials on a sailboat or speedboat. If you are the tallest thing in the area, like standing in a speed boat, then that is two bad things for attracting a strike. Antennas on speedboats or metallic appurtenances on sailboat masts can be grounded to create a lightning protection system for the boat. Chapter 8 of NFPA 780 titled “Protection of Watercraft” covers this information.
Have there been any studies on lightning protection predictors and warning systems, and are they accurate?
We do not have information in this office on lightning detection equipment ("predictors") and warning devices. However our Supplier Member Thor Guard, Inc. specializes in this part of the industry. Their contact information can be accessed from this site under the "Membership Directory" tab - click here to view. Most product information can be accessed on their site [www.thorguard.com]. There are several devices from a simple "field mill" device which is impacted only by increases in electrical field in close proximity to a full blown computerized tracking system that shows storms approaching an entire metroplex.
Aren’t most houses grounded? If the pipes that leave the house go underground then why is this dangerous? Assuming most houses have plastic piping these days which is a lower conductor of electricity than the older copper or metal pipes.
Houses are grounded from the standpoint that they have an electrical system ground, communication system ground, maybe a data system ground, and metallic piping systems (water, sewer, gas) that enter the ground. This is a good and a bad thing. Lightning wants to get to ground by the easiest method available. If allowed to advance with no control mechanism through a structure, it may move from grounded system to grounded system “jumping” or side-flashing through the house. When these various grounded systems are not intentionally interconnected or bonded together near grade (which sadly is typical of most houses) then the jumping can occur from a less suitable ground path (a poorly grounded water line) to a better path (the electric service ground). When lightning jumps through free air, it can be dazzling as in “ball” lightning. When it jumps through building materials it may cause fires or even explosion from superheating. Plastic piping is not a conductor, but a system with partially plastic and metallic sections can lead to this side-flashing phenomena.
Do I need a grounding system connected to a weathervane?
Generally something that is tall, metallic and pointed like a weathervane can release ions more easily making it a target for a lightning attachment. A weathervane should be provided with a path to ground for lightning, but this is not a full protection system for a building. This depends on the height of the vane and the length or size of the building. The only way to fully protect the structure is with a complete lightning protection system according to the Standards. A professional installer can review this with you.
I am interested in protection for a 40 ft. stainless chimney above a house on a flat point of land on Lake Ontario that has absolutely no vegetation other than grass for several hundred meters in all directions. What would you recommend?
Protecting a chimney only is probably not sufficient to provide total protection for your residence, but a 40 ft. metallic body with edges and corners is a likely candidate for a lightning attachment. Included on our website is a brochure labeled "Lightning Protection for Home, Family, and Property" click here to view or print this brochure. You may also find a listing of member companies in your area to provide additional information on a complete system of protection, click here to search by state.
We have copper strips along the seams of our roof. Does that offer protection of any sort by distributing the electrical current of a lightning strike? We also have a newly installed roof. What is the minimum lightning protection system that will not affect this roof e.g., attachments to one or two chimneys that sit above the roofline?
The copper strips on your roofing are really not designed to transfer lightning. They are normally not thick enough to take a direct lightning strike without burning through, and they may not transmit the lightning without suffering some mechanical damage. The other question would be "where are they distributing the lightning current to?" These items are not normally connected to an effective grounding system. Deciding on a proper protection plan and the suitable location to mount air terminals will necessarily require a site visit or some plan review of your structure by one of our member companies. You can view a listing of our member companies in your area on this site, click here to search by state.
I own a historic country Inn in Ontario, Canada that was built in 1881. Unfortunately it was hit by lightning and burned to the ground in 1891, then rebuilt as an exact copy of the original. How often does a strike result in fire? I see quite a bit of information regarding other lightning damage but I can't find anything on fire damage.
If a lightning attachment occurs to insulated building materials, the result is super-heating of the non-conductive items and either fire or explosion. Lightning is variable in intensity, so there is variation in the results. Lightning is also looking for the "best" path to ground, so it seeks wiring and piping systems which may be fairly accessible within attic spaces and walls. If the lightning doesn’t spend a lot of time on insulated materials before reaching a valid ground path, then damage may be minimized, or it may not. There is variability in the cause and effect, so it’s pretty hard to predict accurately. The insurance industry reports that 5% of all claims are lightning related in the U.S., which amounts to over $1 billion yearly. They do not differentiate between fire loss, and electrical or communication device losses, although some percent is related to lightning striking utility lines and entering structures. Even when lightning is carried in on service lines, it may cause massive failure of attached equipment creating a fire. Many wood framed structures catch fire from lightning attachments, while larger steel framed buildings survive with less damage, although lightning attachments can rip apart sections of roof or wall panels from all metallic buildings.
I currently have lightning protection installed on my house. Earlier this year, our lightning rods were struck by lightning. Should I have a contractor inspect the system? The rods are brass and one of the rods appears to be white in color and the point is blunt.
Generally, a properly installed lightning protection system will function effectively even with a little "blunting" of the lightning rods or air terminals. If they were very "sharply pointed," there may be some slight melting of the tip with an attachment. The rod should continue to function, and today some systems use blunt or rounded tips on terminals in the initial installation. These have been shown to be a little more effective in attracting strokes, and in locations where air terminals are required in high traffic areas (on handrails, for example) it avoids any personnel injury concerns.It is a good idea, howerver, to have your lightning protection system inspected at regular intervals. You don’t say when the original installation was completed, but it is a good idea to do your own personal inspection on an annual basis. You can see that terminals are properly screwed into mounting bases, splicers or connectors don’t have any loose wires, cables are still anchored to the building, and there are no damaged cables or disconnected parts. About every 5-years it is a good idea to have a lightning protection professional review the system. This can assure that any changes to the structure are covered, and they will review all the existing components. A lightning protection system is a passive grounding system - you can’t flip a switch, or turn a valve to see if it’s still working - so it should be reviewed at intervals for continuous satisfactory performance.
Why is it that I don't often see lightning protection on single-family residential properties?
In some areas of the country it is very common for houses to have lightning protection systems. If you look at Annex L of NFPA 780, there is a risk assessment calculator for structures. Certainly the fact that residences are smaller buildings may be in areas of lower lightning activity, or do not have the occupancy of other structures can have an impact on risk or consequences. It seems that a more pertinent factor may be whether there is anyone in a local area promoting and selling lightning protection, thus raising awareness of the fact that lightning protection is effective and affordable. In the early part of the last century, insurance companies allowed credits for lightning protection systems for some residential structures particularly those remote from fire protection. Today, most insurers just lump lightning losses with all fire losses, rather than giving a separate credit. This is an area that we continue to work on to make protection more affordable. It may seem more likely that lightning will strike larger buildings, but it is a fairly random occurrence in any area so it depends on how much exposure you can stand. I have lightning protection on my house. I’m building a new house with lightning protection on it. In fact, I don’t remember ever living in a house without lightning protection on it.
I'm interested in installing a lightning protection system on my home. Can you advise me what type of system I need and how I can install one?
Lightning protection installation is a specialty trade, and you may wish to consult with a professional in the industry. Please click here to search by state for an installer near you. They may be able to assist with design drawings and materials to service your needs.