Indoor dangers and precautions during thunderstorms

from Bottom LineSecrets 

ightning is far more dangerous than most people realize. It kills 50 to 75 people annually in the US and injures between 500 and 750.

Lightning also is a lot more common than most people realize. Every year in the US, between 25 and 30 million lightning strikes hit the ground. Around the world, approximately 2,000 thunderstorms (where there’s thunder, there’s lightning) are occurring at any given time, with as many as 100 lightning strikes every second. About two-thirds of all thunderstorms in the US occur in June, July and August.

At least 95% of lightning deaths occur outdoors. If you see lightning, get inside your home or a large building immediately.

To learn more about lightning, Bottom Line/Personal talked to Ronald L. Holle, a weather consultant and former meteorologist with the National Severe Storms Laboratory...

Is it dangerous to talk on a phone during a thunderstorm? Corded phones are extremely dangerous during a storm. Home phone lines are protected with surge devices, but these defenses can be overwhelmed should lightning hit a nearby power pole. Someone dies every few years while talking on a phone during a lightning strike.

Caution: Homes in isolated areas are more vulnerable because they don’t share power poles with as many neighbors. In areas with multiple homes, the electricity is more likely to be “diluted” because it splits in different directions.

Portable (cordless) and cell phones are safe to use during a thunderstorm.

Should I unplug my computer and TV during a storm? No, not during a storm. Electronic devices should be unplugged before a storm arrives. A few years ago, a man in Phoenix unplugged a device at the precise moment when lightning struck. He was thrown across the room.

Every year, the insurance industry pays out about a third of a million dollars in claims for losses due to lightning. Many of these losses involve electronics that are blown out by power surges.

It’s a good idea to protect electronic equipment -- stereos, TVs, computers, etc. -- with surge protectors. Good-quality ones typically cost between $50 and $100. Like the surge protection built into houses, however, they don’t offer 100% protection. Unplugging devices before a storm is the best approach.

Can I get electrocuted in the shower or bath? There was a report a few years ago of someone who was killed by lightning when taking a shower. Faucets, knobs and other metal fixtures are natural conductors of electricity. So is water. A lightning strike that hits your house -- or even comes close -- could potentially carry enough electricity indoors through these natural conductors to cause injury or death.

How safe am I in a car during a thunderstorm? A fully enclosed metal-topped vehicle is generally safe. (A convertible with a vinyl or cloth top is not safe.) The metal-topped vehicle may protect you for the same reason that buildings do -- the lightning travels through the framework and to the ground. Even if you happened to be touching a metal component, such as a door handle, most of the electricity would flow around (not through) you.

There have been cases in which a lightning strike vaporized a car antenna and broke the car’s windows, but the people inside were unharmed.

Some people think that it’s the rubber tires that make a car safe. Not true. A few inches of rubber can’t possibly “ground” a car.

Is it really that dangerous to be under a tree during a thunderstorm? It’s one of the most dangerous places you can be. Lightning tends to hit the tallest objects in an area. Trees are a natural target, but the lightning doesn’t stop there. Electricity always seeks the easiest path to the ground. Since people conduct electricity better than trees, the lightning may jump sideways (a “side flash”) if you’re within three to six feet of the trunk.

Is it true that golfers often get hit by lightning? Fewer than 5% of direct lightning strikes have involved golfers. However, golfers do share with other outdoor enthusiasts the two main risk factors for lightning strikes -- they’re out in the open, and they’re often higher than the surrounding terrain.

Water activities -- boating, swimming, etc. -- also are risky. The current from lightning hitting water or a boat travels across the surface of the water for tens of yards and can be deadly within that distance. Check weather reports, and stay off the water if there is a chance of a storm.

How can I tell if lightning is close enough to be dangerous? A thunderstorm doesn’t have to be overhead to be dangerous. When you see a lightning flash, count the seconds until you hear thunder. If the interval between lightning and thunder is 30 seconds or less, get inside a substantial building or a metal-topped vehicle. Wait 30 minutes after the last flash before going back outside.

Does lightning ever hit the same place twice? It happens all the time. The Empire State Building gets hit an average of 23 times a year.

Should I close house windows during a thunderstorm? Most people do close windows, if only to keep out the wind and rain. However, lightning is no more likely to strike through an open window than a closed one.

Caution: Always close windows if there’s a tree nearby. You also might want to close blinds or curtains. A lightning strike can cause the bark to explode off the trunk, and the bark can travel about 50 feet. People have been killed by flying bark. A window might offer some protection.

Does it make sense to get a lightning rod for my home? Several hundred thousand homes and small businesses are hit by lightning each year in the US. But because of grounded electrical and plumbing systems, electricity from a lightning strike flows around you -- through walls, plumbing and wiring -- and dissipates into the ground. (Small sheds, picnic pavilions and the like are not safe from lightning.)

These days, lightning rods are usually used to protect hospitals, schools, police stations and similar structures. When lightning hits, a lightning rod and its attached thick cable take the surge in current safely to the ground.

A lightning rod on your home is not necessary, but it can offer some peace of mind. The rod is more likely to take the hit than the roof or another part of the house. Having the rod take the hit means that the massive current surge has a preferred path to follow. Otherwise, the current rips through the house and looks for something to carry it, usually the wiring or plumbing. But if the current doesn’t find these paths very quickly in a short distance, then fire and other damage can occur.

A rod costs about $1,000 or more installed. Installation must be done by a licensed professional who specializes in lightning protection (check the yellow pages, or search under “lightning rod installation” on the Internet).