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The Straight Dope 

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An Australian man was talking on the phone while sitting on a kitchen stool with his right leg touching the dishwasher. Lightning struck the phone line somewhere upstream, traveled through the line, fried the phone, and slammed the guy into a wall. He was knocked out for a few seconds and for a minute couldn't breathe or speak. Branching red, fernlike marks on his skin, known as Lichtenberg figures--the traces of the skittering current--extended down his neck, across his torso, and down his right thigh to the point where what was left of the bolt entered the dishwasher. His body hair was singed and his right leg was paralyzed. He recovered fairly quickly but three months later still had mild hearing loss.


Lightning causes way less damage to houses and the people in them than it used to because most buildings and utilities now are well grounded. Research by Ron Holle, a meteorologist formerly with the National Severe Storms Laboratory, suggests that out of a typical 75 U.S. lightning fatalities per year, one person on average is killed while using the phone, another two or three die due to lightning conducted through pipes, wiring, etc, and one or two are killed by lightning-caused house fires. It's estimated that 10 people are injured by lightning for every one killed. Considering there are 25 million cloud-to-ground lightning flashes in the U.S. annually, that's not many. By contrast, in the early 1980s, 60 to 80 Australians were injured by lightning each year while on the phone, a rate roughly 45 times higher than the comparable rate in the U.S. At the time Australian phones weren't connected to the house electrical ground. Now they are.

Effective as grounding is, if lightning strikes close enough, the fearsome current involved--anywhere from 10,000 to 200,000 amperes--can defeat even the most reliable protective measures. That means parental advice about staying off the phone, out of the shower, and so on during lightning storms is still worth heeding. Even a relatively small jolt can fry delicate electronic equipment. According to Holle, the U.S. insurance industry pays 300,000 claims annually for home damage due to lightning, a large fraction of which involve electronics. Cheap surge protectors don't offer much security; if you can't afford the $50 kind and your computer contains critical data, unplug it before (not during) an electrical storm.




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