Frequently Asked Questions about Lightning Protection
Prepared 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.
Common Misbeliefs about Lightning
(Old Wive's Tales)
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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.
Prepared by: INDEPENDENT PROTECTION COMPANY, INC.
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