If You Hear Thunder, You Should Go Inside

Posted: May 10, 2000

Philly's own Ben Franklin only had it half right when it came to lightning.

He made a leap of science when he figured out lightning was electricity. But he was wrong, wrong, wrong when he went out into a storm in 1752 with a metal key, hooked it up to a kite and held onto a wire as the kite rose into the clouds.

Try that a few times and you can turn yourself into a statistic. Franklin proved his point, touching off a spark when he tapped his hand against the key. But he could have become a very dead scientist very easily, lightning experts say.

The message for the rest of us: Stay away.

Although there are no foolproof ways to protect people against lightning, about three-fourths of deaths probably could be eliminated if people followed the "30-30 rule," says Ron Holle, a research meteorologist with the National Severe Storms Laboratory.

The 30-30 rule, adopted by the American Meteorological Society two years ago, states that people should move to a safe place if thunder follows lightning within 30 seconds. And they should remain sheltered until no thunder has been heard for 30 minutes.

But what's a safe place? The best bet is a substantial building with plumbing and wiring. Those systems are grounded and should carry electricity down to the ground. A shelter with only a roof and side supports - and no plumbing or grounded wiring - is unsafe, the National Weather Service says.

Other bad spots include high places, open fields, areas near isolated trees or poles, bleachers, convertibles and golf carts, small boats and water (making swimming pools, rivers, and the ocean off limits). A clump of low trees is better than a single tall tree or an open field.

A closed vehicle is a decent shelter - not necessarily because of the rubber tires, which may be blown out by a bolt, but because the metal of the car should conduct the charge to the ground.

Even inside a building, your mother's age-old warnings make sense. Don't talk on the phone (cordless phones are OK, though loud noise could damage your ears), don't take a shower or wash your hands, don't touch metal door frames or wiring or plumbing.

Oh, and unplug the computer and modem. A good lightning bolt can fry electronic gear, even overpowering a surge protector.

If someone is hit by lightning, the victim won't retain an electrical charge that could zap others. Companions should start resuscitation right away.

And some things don't help, though many people think they do. Experts say wearing sneakers - or leaving your cleats behind - won't really save you.

"It absolutely doesn't matter what you wear," said Holle. "Just don't be there."

Send e-mail to smithra@phillynews.com

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