Each year, thousands of homes and other properties are damaged or destroyed by lightning. It's responsible for more deaths and property loss than tornadoes, hurricanes and floods combined. Lightning is the only disaster that we can economically afford to protect ourselves against. If struck by lightning, a building will generally sustain more damage when there is no lightning protection system present.
Lightning is the visible discharge of static electricity within a cloud, between clouds or between the earth and a cloud. 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 charges flow to the bottom. When the negative charge moves down, a pilot leader forms. This leader rushes toward the earth in 150-foot discrete steps, ionizing a path in the air. The final strike down generally occurs to a high object and the major part of the lightning discharge current is then carried in the return stroke, which flows along the ionized path.
Lightning Protection Systems
A lightning protection system provides a way for the discharge to enter or leave the earth without passing through and damaging non-conducting parts of a structure, such as those made of wood, brick, tile or concrete. A lightning protection system does not prevent lightning from striking; it provides a way for controlling it and preventing damage by providing a low resistance path for the discharge of lightning energy.
How to Prepare for Lightning:
- Install a lightning protection system that complies with current nationally recognized codes. Lightning protection systems consist of air terminals (lightning rods) and associated fittings connected by heavy cables to grounding equipment. This provides a path for lightning current to travel safely to the ground.
- Install surge arresters at your utility service and telephone equipment to prevent surges from entering your home or other structures on power or telephone lines. Surges are diverted to the ground, and both wiring and appliance are protected.
- Install transient voltage surge suppressors in receptacles to which computers and other electronic equipment are connected in order to limit the voltage to 1.5 times the normal voltage (maximum for solid state devices).
Lightning Safety Tips:
If you are caught outdoors immediately get into a building or vehicle. Don't wait for the rain to begin. If you're unable to get inside, remove all metal and your baseball cap, crouch down with feet together in pitcher-stance, duck your head and cover ears, becoming as small a target with as little contact with the ground as possible.
When you first see lighting, avoid being near trees, water, high ground or open fields. Picnic and canopy shelters should also be avoided, as well as metal objects like flag poles, light poles and bleachers.
If you are indoors during the storm, stay away from doors and windows. It's also important not to use a telephone to avoid being struck. You should also unplug any electronic equipment and appliances to protect them from the possibility of power surges.
After Lightning Strikes:
After the storm is over, follow these steps to protect yourself from harm:
- Wear protective shoes and watch for broken power lines, shattered glass, splintered wood or other sharp objects.
- If it can be done safely, turn off damaged utilities.
- Take steps to prevent additional property damage from rain, wind and looting.
- Keep your receipts for materials purchased to protect your property from further loss; these expenses may be reimbursable under your homeowners insurance policy.
- Make an inventory list of all damaged contents.
This information is provided by Underwriter Laboratories Inc. (UL). In the lightning protection field, UL has been serving home and building owners since 1908. Today, UL has a large number of trained lightning protection field representatives located throughout the United States. UL inspects sites ranging from cow barns to missile silos, from golf course shelters to high-rise building systems. In fact, some of the most famous buildings in the world are protected by UL Master Labeled lightning protection systems, including the White House, the Sears Tower and the Washington Monument.