Frequently Asked Questions about Lightning ProtectionPrepared for property owners considering lightning protection for their residence, farm buildings, condominium, summer cottage, winter home — questions most commonly asked by owners considering lightning protection — some questions have several answers.
Will a lightning protection system really protect my property, family and contents of my building from lightning?
Absolutely. A lightning protection system properly installed in accordance with the latest standard requirements is approximately 99% effective in preventing potential lightning damage. These statistics are furnished by the Underwriters Laboratories on UL Master Label inspected systems starting in 1923 to the present.
I didn't know lightning rods were used anymore. Years ago, I used to see them on barns in rural areas. Why don't I see more lightning rod systems today on newer buildings?
Many lightning protection systems on newer construction, especially residences, are concealed or built in during construction. Only the 10" neutral colored points or air terminals are visible from the exterior of the building. The cables, connectors, clamps, etc. are coursed underneath the roof, built-in between the rafters and the studs during construction and grounds are located either in the basement or outside the foundation below grade.
How do I know my system will be properly installed?
Deal with a local established lightning protection installation company or contractor. Do not deal with transient fly-by-night companies passing through the country offering "a good deal". Insist that the salesman or lightning protection representative show credentials such as being a member of the local Chamber of Commerce and ask for a list of customers in your immediate area. Also, ask for your system to be in accordance with the Underwriters Laboratories Master Label certificate requirements and/or certified by the Lightning Protection Institute. Remit your payment after the installation has been completed and you will receive the UL Master Label certificate or LPI Certification by mail.
I have my building insured - why do I need lightning protection?
Even though you have your building insured, most policies have a first dollar deductible paid for by the owner before the policy takes effect. A lightning protection system will eliminate all future lightning damage; therefore you will not need to pay $250 to $500 deductible. In reality, this reduces your cost of insurance by eliminating the deductible resulting from lightning damage.
The loss resulting from lightning damage is very seldom insured 100% of replacement value. An insurance policy is usually written with an 80/20 clause for depreciation or is deducted. From an insurance standpoint, lightning protection is a good investment.
How susceptible am I or what is my lightning risk during a thunderstorm?
This depends on what part of the United States you are located. General Electric statistics show that lightning strikes each square mile from 1 to 1-1/2 times the number of thunderstorm days per year. In the state of Florida, which averages from 80 to 100 thunderstorm days per year, this means that lightning will strike each square mile of Florida from 80 to 150 times each year. In the Midwest, which averages from 40 to 50 thunderstorm days per year, this means that lightning will strike each square mile from between 40 to a maximum of 75 times each year.
How does a lightning protection system work?
A properly installed lightning protection system intercepts the lightning bolt between cloud and earth and harmlessly conducts it to ground without damage. In reality, a lightning protection system raises the ground from grade to the tips of the points or air terminals.
I have tall trees right next to my house. Won't they protect me?
Lightning is no respecter and trees are not a good conductor of electricity. Lightning may strike a tree and then flash over from the tree roots into the house via the water, gas or electric lines or some other means. A lightning protection system installed on the home offers only protection to the home and a system installed on a tree offers protection only for the tree. If a system is installed on a house and tree that are with 25 feet of each other, the two systems should be interconnected to create a common ground.
How many years will a lightning protection system last?
With proper maintenance and periodic inspection, the system should last as long as you own your property. Many lightning protection systems have lasted 50 years with proper maintenance.
I have heard that lightning rods attract lightning.
A lightning rod system will not attract lightning nor will a system repel a strike. At the time the leader stroke leaves the clouds starting downward toward ground, the equal and opposite ground charge is seeking a path upward to meet or neutralize the cloud charge. If the cloud charge is over a building with a lightning protection system, the earth charge uses this system and dissipates out the top of the air terminals and the two charges meet at a location called striking distance, usually 150 feet, more or less, above ground.
Does lightning ever strike more than once in the same place?
Yes, very often. The Empire State Building in New York City, which has a lightning protection system, is struck on average 100 times a year without damage to the system or building.
The fact that lightning strikes multiple times in a location is a good indication that it will strike again if the object or building is still standing after the first strike. Localized conditions, mineral contents in the sub-soil, etc., are all reasons why lightning may strike many times within a given area.
During thunderstorms I have electrical problems within my building. Will a lightning protection system prevent this from happening?
Yes, in addition to the lightning protection system consisting of air terminals, conductor cables, clamps, fasteners, 10 foot grounds, etc., a secondary lightning suppressor is installed on your electric service entrance panel to prevent current fluctuations (called lightning surges) during a thunderstorm. These power surges can result even when lightning strikes nearby.
Your price is too high!
You purchase a lightning protection system for your residence or building only once and it's important that the system be installed according to the latest code requirements and that quality materials be used. Over the lifetime of your system, the cost is pennies per thunderstorm which, in reality, is very inexpensive when you consider a system properly installed is over 99% effective.
There are transient companies that install lightning protection system on homes and other structures throughout the country. Prices charged could be very low or ridiculously high. If you have any doubt about the company providing an estimate, ask him for his credentials and for any other installations in the area that have been provided. Run your checks before you agree to an installation. It is often after the fact that people realize they paid too much money and suspect that the installation doesn’t meet the national standards. By then, it's too late.
Is it dangerous to stand near a lightning conductor during a thunderstorm?
No, not if a conductor is properly grounded.
Why is it necessary to have more than one ground on a lightning protection system?
All lightning protection standards call for a minimum of two downleads and grounds in order to provide a circuit or two-way traveling path to ground. Also, a minimum of two grounds facilitate adhering to the standard requiring "common grounding" with the metal water pipe, electric ground, telephone ground, gas piping as well as bonding to metal parts of the building such as eaves, downspouts, metal exhaust fans, ventilators, etc.