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Lightning Doesn't Have To Strike Your House To Cause Serious Damage

Updated: Jul 9, 2021


Lightning in night sky with home in foreground with lights on inside

You may have heard the maxim, "When thunder roars, go indoors." Inside you'll undoubtedly be safer

yourself, but your home is always at risk, even if a strike is a mile away. In fact, Richard Kithil of the National Lightning Safety Institute says indirect lightning strikes are 2000 times more likely to cause "mischief" than a direct strike.


Lightning is the most consistent weather killer on earth. It kills more people than hurricanes, tornadoes, or floods. Each year, approximately 24,000 around the world are killed by lightning. Another 24,000 are struck and injured but survive.


In the United States, only three out of 10 people struck by lightning die. The immediate cause is a heart attack. More often than not, lightning flashes over the outside of a victim. The heat and percussion of the strike, however, can cause serious injuries.


We all know not to use water during a thunderstorm, stay away from windows, and get off the phone. But here's how lightning can damage your home even if there isn't a direct strike.


How Lightning Travels Into Your Home


Invisible Fences


In western Virginia, a homeowner installed an invisible fence system to contain her golden retriever. During a lightning storm, a bolt struck the ground in a next-door neighbor's yard. The current traveled through water in the ground and was absorbed by the wiring used in the invisible fence. That current then traveled into the home, "frying" TVs, stereo systems, the AC unit, appliances, and more. The total cost to repair the damage was well into the five figures.


Water Pipes


Lightning can strike up to 2 miles away and travel through underground streams and water pipes into your home. If a water-using appliance is running, the current can cause damage to the appliance directly. It can also shock anyone using a shower or washing his hands/dishes.


Concrete Floors


Concrete floors are reinforced with metal that can conduct electricity from ground strikes. Experts advise not standing or sitting on concrete during a lightning storm. It is also advisable not to place sensitive appliances or equipment directly on concrete as they can also be damaged.


Wiring


If the electricity from a lightning strike is conducted by a home's gutters, windows, concrete floors, and other exterior conductive materials, it can jump to the home's electrical system. A direct hit or one nearby can cause an explosive surge that will destroy the wires. These wires can melt and ignite surrounding materials. Individual surge protectors can protect against small surges but are unlikely to prevent damage from a direct strike. Whole house surge protectors will protect your wiring, but it is always a good idea to unplug appliances and electronics during a storm.


Metal Windows


Aluminum windows can conduct electricity, though not as well as other metals like copper and steel. If a lightning strike is close enough, the coatings on aluminum windows and railings can melt.


Shock Waves


Thunder is a shock wave caused by the rapid expansion of heated air around lightning. These shock waves can cause structural degradation and cracking in concrete, brick, cinderblock, and stone, depending on their intensity and proximity. Brick and stone chimneys are particularly susceptible as the vibrations can damage the mortar and shake the flashing loose.


 
Benjamin Franklin said, the only absolutely safe place to go in a lightning storm is "inside sitting in a silk hammock reading a good book."
 

What to Do After A Lightning Strike


Fire and Scorching


A direct strike on your home should be called into 9-1-1 immediately, even if you don't see any fire or scorching. Fires inside the walls and in the attic can smolder for hours undetected. The fire department can use a sensor to detect heat within your walls and quickly address any issues.


If there is no fire, you should contact a professional contractor to schedule a complete inspection of your roof, chimneys, roofing shingles, siding, gutters, and walls for damage.


What Insurance Should Cover


Your homeowners policy typically covers damage from a lightning strike. If you have a professional contractor inspect your home and damage is found, Mutual Assurance will pay for the inspection and the damages. If the contractor finds no damage, the homeowner will pick up the cost for the inspection.


Please remember that keeping your homeowner policy up to date is essential for you to get the correct coverage.


Some Lightning Facts You Probably Didn't Know


Lightning doesn't actually travel at the speed of light. The flashes we see do (670,000,000 mph), but electricity/power travels at only 270,000 mph.


The most lightning struck location in the world is Lake Maracaibo in Venezuela. Thunderstorms here occur 140-160 nights each year with an average of 28 strikes per minute. Some storms last up to 10 hours, which would equate to 40,000 strikes in one night.


Helicopters can cause lightning. While flying, a copter acquires a negative charge. When it passes through an area that is positively charged (like the base of a cumulonimbus cloud) it can trigger a lightning strike.


There are 1.4 billion lightning strikes every year. That's 44 strikes every second.


Lightning destroys trees, but it can help other plants grow. The extreme heat of a lightning strike causes nitrogen to bond with oxygen, creating nitrogen oxides. These oxides combine with moisture in the air that falls as rain and waters plants with nitrate rich water.


The actual width of a lightning strike is only about 3/4" to 1 1/4" wide. The average length, however, is 2-3 miles.


The temperature of a lightning strike is 30,000°C/54,032°F. That's five times hotter than the sun.


While you have always thought that counting the number of seconds between seeing lightning and hearing thunder tells you how many miles away the strike is, this formula is wrong. The right way to determine the distance away is to count the number of seconds between the flash and the boom and then divide that number by 5.


And lastly, until the late 18th century, it was believed that ringing church bells repelled lightning. This is why many of the bells bore the inscription fulgura frango, meaning "I chase lightning." During a thunderstorm, bell ringers would run to the tower to ring the bells, one of the worst places to be in a storm. Between 1753 and 1786, 103 bell-ringers in France were struck by lightning and killed. The custom was subsequently banned.







Sources: CDC, National Lighting Safety Institute

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