thebeave

Lightning was one of my specialties in my previous job, so I think I can clear up some things here. First, the lightning does not necessarily have to directly strike the phone wiring for you to get a nasty shock. Lightning produces a very intense electromagnetic field that can induce high currents in nearby wiring. Essentially, your wiring (phone and electrical) acts like a giant, low frequency antenna, and the lightning electromagnetic field acts like a very intense, nearby (but short duration) radio station. The amount of current induced in the phone wiring can be enough to easily destroy electronics and give you a very nasty shock.

The lightning bolt originates in the cloud as a low current (relatively) "bolt" and makes its way toward the ground in a jagged, stepped fashion of 150 ft increments or so. It is called a stepped leader, I believe. This is not what you see when you witness a strike, as this leader is generally too faint to see with the naked eye. When the leader gets close to the ground (a few hundred feet or so), it induces several faint discharges from nearby ground objects (generally from sharp, pointed objects like trees or poles where the local electric field is highest). One of these discharges will connect with the stepped leader and the others will disappear. The two connecting discharges meet above ground (about 150 ft or so) and complete the current path to ground. There is a huge store of charge waiting at the ground that then rushes through the low resistance current path created through the atmosphere by the stepped leader, resulting in the bright flash and subsequent thunder. The current can be as high as about 200,000 amps, but the average is around 20,000, if I remember correctly. Lightning is really neat stuff. It's probably the only thing I missed about that last job.

Tom Sawyer

OK, so it sounds like it's possible to get electrocuted whileon the phone but not very likely.

Does anyone know if this has ever actually happened? I'm talking about recently with the protections on the system that they currently have and not before circuit breakers and the like were installed. Because I've never actually heard of this really happening.

Glory

thebeave,

Thanks for the cool lesson.

Glory

Jerry Love

Yes, though it's quite likely to be in the "big antanna" realm, as it was far from fatal.

Obvious methods include lightning hitting on the same side of the breaker as you are.

Mageth

<a href="http://www.emedicine.com/plastic/topic517.htm" target="_blank">Here's</a> a good article on lightning-related injuries, and includes a section on hearing damage resulting from ligthning, often in telephone-related cases.

ImGod

Here's a site with a good overview of lightning.

<a href="http://skydiary.com/kids/lightning.html" target="_blank">Lightning for Kids</a>

My neighbor out in the country where I grew up had his television antenna struck by lightning. It destroyed his television, then his speakers. It burned two stripes in the carpet and the back of his kid’s legs by overheating the speaker cable. He had lightning rods on his house, but the antenna wasn't grounded to the system.

Mageth

When I was a kid, I saw a phone literally smoke after a lightning strike which didn't directly hit the house. I've been cautious around phones ever since.

Dark Jedi

There was a thread a little while back where someone's house was struck. It included several pictures of the exploded phone and blackened wall where it used to hang....

NumberTenOx

Many years ago I saw a demonstration of the huge Van de Graaff generator at the Science Museum in Boston. They had a discussion of lightning and its effects.

The claim was that no one struck by lightning lives to tell the tale, because the current is just too strong. All people who think they have been struck by lightning, have actually been very close to the strike, and had reverse currents induced in their bodies (as mentioned by thebeave above). A typical example would be a strike hitting the tree; the current through the tree would induce a large reverse current in whoever was standing nearby (this is described - I believe erroneously - as "flashover" in the eMedicine link above).

I believe this. Think of the power required to jump through air, and cause that flash and that noise. Think of that power going through your body.

They demonstrated this by creating arcs near a human-sized panel with some kind of light bulb strapped to it (I think fluorescent, but could have been neon or something else). The strikes clearly induced the light bulb to shine brightly, with no direct electrical contact.

On a personal note, I've always had a fascination with lighting, even though (or possibly because) we don't get very much here in the Northwest USA. My wife is from Iowa; she has joked that the mid-west tends to be more religious because the lightning there "scares the hell" out of people.

[ November 02, 2002: Message edited by: NumberTenOx ]</p>

thebeave

I think many people have been struck directly by lightning and lived to tell, and, yes, also many have been hit by a "sideflash" while standing next to a tree, pole, etc. People have been struck standing in the middle of a field where there was no other tall object to sideflash from, so direct hits are real. It could be that they survived because they got hit by a relatively small stroke. At the low end of peak current statistical distribution, it is around 2000 amps and it is very short lived (measured in microseconds). Many other factors come in to play also as to had badly hurt you will be or if you die. Things such as the current path thru the body, wetness of the body (path resistance), health of the victim, entry and exit points, etc. Many people suffer chronic pain and ailments the rest of their lives and there are support groups out there for the victims. I've even heard of a few times where people had an ailment cured after getting hit. I remember hearing how a deaf person got their hearing back after getting hit! I'm sure they thought that Jesus had something to do with it.