When Lightning Strikes

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The morning sunshine has given way to dark, threatening clouds. By afternoon, thunder can be heard in the distance. Then, in an instant, your barn is struck by lightning and a fire has started. Could this disaster have been prevented?

LIGHTNING EXPLAINED

Before looking at ways to protect your facilities and animals, an overview of what lightning is will help. Although the process is not entirely understood, it is known that clouds generate electricity. The electricity builds up until eventually an electrical discharge, the bolt of lightning, is dispersed. Lightning can occur between clouds, from cloud to ground or from the ground up to a cloud, although strikes from the ground up account for less than 10 percent of strikes. The light we see is the energy being released from air molecules resisting the strike, while thunder is the sound of a superheated column of air rushing away from the lightning strike. Of the more than 1,000 people who get struck by lightning each year, more than 100 die. Many of the injuries happen not from a direct strike, but from ground current, the electrical charge traveling away from the object that was struck. Therefore, if you lie prone during a storm, the electricity will travel through the body to the heart. The correct position is to crouch down, get on the balls of your feet, and keep your hands off the ground. If you do, then the electricity will go from leg to leg and not through your heart. Unfortunately, horses, because of their stance with all four legs making contact with the ground, stand a higher chance of having the electricity go through their heart and killing them.

PROTECTING HORSES

The safest place for horses during a storm, explains James Barnard, president of Northeast Lightning, LLC in Bloomfield, Conn., “is in a protected structure. A barn where a lightning protection system has been installed is best.” If you have horses in a pasture, by the time you hear thunder approaching, it is probably too late to risk going outside. “Run-in sheds in a field,” continues Barnard, “can be made safe by installing lightning rods and keeping the horses at least six feet away from the conductors [wires connecting the lightning rod to ground]. This can be effective as long as the horses are not on a dirt floor, because ground current from a nearby strike can travel along the dirt to the horse.” Barnard suggests a raised wooden floor. Rubber mats on top of the wooden floor act as insulation and provide added protection.

For horses kept in a pasture, there are numerous products that claim to dissipate a strike and keep animals safe. These include static dissipation arrays, preferred strike points, and early streamer emission air terminals. The idea is that these attract a strike to a “preferred” point and protect a claimed radius of up to 328 feet. So one or two of these units placed around a field will, in theory, protect the interior of the field.

Before you rush out to purchase one of these products, Barnard warns that they “do not work! The manufactures make many claims and because the lightning protection industry is not regulated, they are able to get away with such claims. But when the Arizona District Court took on these products, the manufacturers could not produce any scientific data to support their claims.” In addition, these products were investigated by the US Standards Committee NFPA 780. The conclusion of their independent study found them to be no better than a conventional lightning rod, and they do not recommend their use.

PROTECTING FACILITIES

Before purchasing a lightning protection system, cautions Barnard, it is imperative that you hire somebody who is certified and self-insured. “Because the field is unregulated, anybody can put a system in, from roofers to electricians and handymen.

“There are two simple things you need to do, and they don’t cost anything. First, insist on LPI [Lightning Protection Institute] certification. That means the installer is an LPI Master Designer and has put five years into learning the trade and has been tested. Without certification, you can run into big problems. Secondly, make sure they install a UL [Underwriters Laboratory] certified system. Insurance companies require the UL master label, which means the owner of the facility is requiring the installer to hire underwriters to inspect the building and give their report to the owner.”

Lightning rods are what most people think of when lightning protection is mentioned, and they are misunderstood in a number of ways. They don’t attract lightning, one is not sufficient for a whole building, nor are they standalone units—they are part of an integral system consisting of rods, conductor cable and ground rods. Explains Barnard, “Lightning rods are active when acted upon. They cannot repel lightning nor can they attract lightning except in a very limited radius. When lightning is going to hit a structure, a lightning rod can divert it up to a 15-foot radius. That is why you see lightning rods spaced 20 feet apart; so the radii will overlap. Lightning will not hit between them; it will hit one or the other.

“A common misconception is that tall buildings, such as a church steeple, only need one lightning rod. But that isn’t true. I’ve had people tell me they just built a new arena and it has three cupolas so they just want rods on the cupolas. My job is to inform them that if they protect just the cupolas, then lightning may strike in between, or hit another part of the building.”

Each system has several components: the lightning rods which intercept the strike, conductors [wires] to transmit the energy, grounding to dissipate the energy to the ground, and bonding, which keeps the lightning from arcing across combustibles to a body of metal, whether it is a skylight, downspout or any other outcropping within six feet of any part of the system. It must be tied into the system for the system to work properly.

The cost of a lightning protection system will vary depending on a number of factors, but expect to spend about 1 percent of your building costs.

Is lightning more attracted to a metal barn than wood? “Neither is more likely to be struck,” says Barnard. “But metal is less likely to be damaged. Unless the metal is greater than 3/16” thick, and most metal barns are not, then the lightning will pop a hole through it and start a fire, but then it will dissipate effectively through the steel framework of the building. But if a wood building is struck, it will start a fire immediately and destroy the building.”

What about electric fences? “Electric fences are tough,” admits Barnard. “Lightning might strike five miles away and still take out your electric fence, because the ground current from a strike goes across the ground, and the fence is right there and grounded numerous times. People will put a surge protector in to protect the power panel, thinking the strike is at the panel, but usually it is coming from the field through the fence. You should install surge protection but also make sure the grounding for the fence is tied into the lightning system.”

Also note that other fences are at risk. Barnard has seen a PVC fence explode from a strike. It was a random shot, but the fence was the high point in a cleared field and so at risk. A lightning protection system is a relatively inexpensive installation which can save your business, and that is invaluable. Concludes Barnard, “Give lightning a preferred path to the ground, keep that path free from tight radius bends, keep it pointing toward the ground or horizontally, bond everything together, and you will have a safe lightning event.”