Lightning Strike?
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From: Far NW 'burbs of Chicago
St. Jude Donor '13
Lightning Strike?
I've always thought the windshield frame + halo in a coupe, or steel frame for the canvas in a vert, would protect us from a (very rare) possibility of a lightning strike.
But in a Q&A about lightning in today's Chicago Tribune, it says:
"Am I safe during a thunderstorm if I'm in a car?"
"That depends on whether your car has a metal roof. A car's metal roof and sides protect occupants from lightning by directing the electricity through the car's frame and into the ground. You're not protected if you're in a convertible or on a motorcycle. Rubber tires don't offer protection."
We know the newspapers always get it right...
I'm guessing that GM has done some testing, but not sure if they release the results.
Anyone know for sure?
But in a Q&A about lightning in today's Chicago Tribune, it says:
"Am I safe during a thunderstorm if I'm in a car?"
"That depends on whether your car has a metal roof. A car's metal roof and sides protect occupants from lightning by directing the electricity through the car's frame and into the ground. You're not protected if you're in a convertible or on a motorcycle. Rubber tires don't offer protection."
We know the newspapers always get it right...
I'm guessing that GM has done some testing, but not sure if they release the results.
Anyone know for sure?
Pro
Joined: Jan 2010
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From: Apache Junction AZ
Electricity takes the shortest path so if your car was struck it would go though the halo and then to ground. If your that worried about it put a handsome looking CB antennae on the roof and run the wires through the path that you can repair the easiest.
Pro
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From: TremontonUT UT
"Am I safe during a thunderstorm if I'm in a car?" You are safer than many objects around you. A very close or direct hit you will be toast. I have been very close to a big strike. It was an explosion. Good luck with your #22 wire carrying several million volts to ground. Later! Frank
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St. Jude Donor '05-'06-'07-'10
Have a read of this thread:
http://forums.corvetteforum.com/c6-c...-lighting.html
and more importantly, the reply (post 44, page 3) by Shopdog which I've quoted here:
http://forums.corvetteforum.com/c6-c...-lighting.html
and more importantly, the reply (post 44, page 3) by Shopdog which I've quoted here:
Originally Posted by Shopdog
I suppose I should comment. I wrote one of the commonly referenced texts on lightning effects and lightning protection, so I do know a few things about the subject.
First of all, lightning can travel miles through open air, a little thing like a rubber tire won't inconvenience it. Trees are the most commonly struck natural objects, and wood is not much better of a conductor than fiberglass. Neither is as good an insulator as air, and as noted above, lightning has no trouble travelling through miles of open air. When you are dealing with voltages in the hundreds of millions of volts range, and currents approaching 20,000 amperes, our common sense notions of electricity derived from our experiences with low voltages aren't too good a guide.
The best thing to have around you when lightning is near is a full metal cage. Not much can insulate against the voltage of a lightning bolt, but the Faraday cage effect works very well to keep charge outside a metal structure. Charge only exists on the outer surface of a closed metal object because charge is free to move in metal, and like charges repel, so the charges try to get as far from each other as possible, that means they stay on the outside. So things inside a closed metal object are essentially immune to the effects of lightning. That's why it is extremely rare for the electrical systems of ordinary metal bodied cars to be affected by lightning. However, a plastic body offers no Faraday cage shielding from lightning.
Lightning does follow electrical law. It will take the lowest resistance path between two points. (It'll also take every other path between those points, with the current of the bolt dividing in inverse proportion to the resistances of the paths in accord with Kirchhoff's law.) Since a tree, person, or car is a lower resistance path between Earth and sky than open air, more of the lightning's current will flow through these objects than will divert through open air around them. The only way to avoid being a primary conductor of lightning is to have a much better conducting path nearby which will hog the majority of the lightning bolt's current. Lightning rods are protective for this reason. They offer a very much better conductive path to Earth than do the structures to which they are attached.
Now lightning doesn't have to directly strike an object to have an effect on it. The 20,000 ampere current of the strike generates an electromagnetic pulse which can induce massive currents in nearby conductors (and less substantial currents in more distant conductors). The latter is the source of the "crashes" you hear on AM radio when a thunderstorm is in the area. But a near strike can induce currents strong enough to do damage to electrical systems. This is probably what happened to the poster's car. Induced currents in the wires of the car damaged some sensor or an input port on one of the computer modules. (Or perhaps the surge only triggered an alarm in some circuit, which will clear on its own after a certain number of start cycles have occurred.)
First of all, lightning can travel miles through open air, a little thing like a rubber tire won't inconvenience it. Trees are the most commonly struck natural objects, and wood is not much better of a conductor than fiberglass. Neither is as good an insulator as air, and as noted above, lightning has no trouble travelling through miles of open air. When you are dealing with voltages in the hundreds of millions of volts range, and currents approaching 20,000 amperes, our common sense notions of electricity derived from our experiences with low voltages aren't too good a guide.
The best thing to have around you when lightning is near is a full metal cage. Not much can insulate against the voltage of a lightning bolt, but the Faraday cage effect works very well to keep charge outside a metal structure. Charge only exists on the outer surface of a closed metal object because charge is free to move in metal, and like charges repel, so the charges try to get as far from each other as possible, that means they stay on the outside. So things inside a closed metal object are essentially immune to the effects of lightning. That's why it is extremely rare for the electrical systems of ordinary metal bodied cars to be affected by lightning. However, a plastic body offers no Faraday cage shielding from lightning.
Lightning does follow electrical law. It will take the lowest resistance path between two points. (It'll also take every other path between those points, with the current of the bolt dividing in inverse proportion to the resistances of the paths in accord with Kirchhoff's law.) Since a tree, person, or car is a lower resistance path between Earth and sky than open air, more of the lightning's current will flow through these objects than will divert through open air around them. The only way to avoid being a primary conductor of lightning is to have a much better conducting path nearby which will hog the majority of the lightning bolt's current. Lightning rods are protective for this reason. They offer a very much better conductive path to Earth than do the structures to which they are attached.
Now lightning doesn't have to directly strike an object to have an effect on it. The 20,000 ampere current of the strike generates an electromagnetic pulse which can induce massive currents in nearby conductors (and less substantial currents in more distant conductors). The latter is the source of the "crashes" you hear on AM radio when a thunderstorm is in the area. But a near strike can induce currents strong enough to do damage to electrical systems. This is probably what happened to the poster's car. Induced currents in the wires of the car damaged some sensor or an input port on one of the computer modules. (Or perhaps the surge only triggered an alarm in some circuit, which will clear on its own after a certain number of start cycles have occurred.)
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Melting Slicks
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From: On the east coast we drive until we die
Just install a long metal rod and connect it to a flux capacitor installed in your car so if by some chance you do get struck by lightning, you can travel back in time to before you were struck and warn yourself not to travel in that area. Of course if you don't travel that same path you wont get struck by lightning and go back in time so you wouldn't be able to warn yourself not to take that path thus causing you to get struck by lightning, which would in turn send you back in time where you....
and so destroys the space-time continuum
Actually that's a good read. I'm sure (hope?) the OP isn't obsessively concerned about being struck by lightning but is merely bringing up an interesting possibility.
and so destroys the space-time continuum
Actually that's a good read. I'm sure (hope?) the OP isn't obsessively concerned about being struck by lightning but is merely bringing up an interesting possibility.
Thread Starter
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St. Jude Donor '13
I'm not worried about meteorites, that Lexan top is really strong!
As for the lightning issue, after reading the replies here and the entire thread that Paul referenced; I still don't know if the Tribune article was correct or not.
As for the lightning issue, after reading the replies here and the entire thread that Paul referenced; I still don't know if the Tribune article was correct or not.
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St. Jude Donor '13
But it's always nice to know, we drive our C6 in any kind of weather on road trips, and have been caught in some massive midwest thunderstorms.
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St. Jude Donor '05-'06-'07-'10
Jim, I think the correct answer is that the newspaper got it partly right. If you read Shopdog's section on Faraday cages, this is what the author of the newspaper piece was alluding to. Electricity will move in the path of least resistance and because of properties of charges, will be forced to the outside of the metal structure (sometimes referred to as the skin effect in electrical wiring). Metal roof, metal framed, metal bodied cars will do more due to these properties of electricity. I think that if a charge were to hit our A pillar directly you'd have a better chance then if it hit the center of our roof panel. We do have some aluminum, magnesium and steel surrounding us in our cars along with air but we also have some plastic and composite that are still lower resistance than air.
Thread Starter
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From: Far NW 'burbs of Chicago
St. Jude Donor '13
I can remember pics in National Geographic about 50 years ago of cars being tested in a "lightning chamber", all we need is a chamber and a volunteer.
During my airline career I can recall having several "static discharges", somewhat like a smaller reverse lightning strike. Exciting but usually no damage. To my knowlege, I never took an actual lightning strike in over 25,000 hours of flying.
During my airline career I can recall having several "static discharges", somewhat like a smaller reverse lightning strike. Exciting but usually no damage. To my knowlege, I never took an actual lightning strike in over 25,000 hours of flying.
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St. Jude Donor '15
"In honor of jpee"
I miss Shopdog, but appreciate the quote of the article, Paul. Since his treatise is that it will follow the path of least resistance, seems to me it will hit maybe both at the same time. The roof and the halo or A pillar. Who knows? I sure don't want to be in the car when it hits, but now saying that....I will be! oh darn...
Le Mans Master
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From: Glassboro New Jersey
I don't know about the occupants, but I can tell you lightning wreaks havoc on a vehicle.
I work for a dealership, and we have 2 cars in the shop now that were hit.
It blew out ALL the modules, the alternator, fuse box, almost anything in the electrical system.
The insurance company totalled one truck because cost of parts and labor to repair exceeded value of the truck.
I work for a dealership, and we have 2 cars in the shop now that were hit.
It blew out ALL the modules, the alternator, fuse box, almost anything in the electrical system.
The insurance company totalled one truck because cost of parts and labor to repair exceeded value of the truck.
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St. Jude Donor '13
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In unison and with a blank stare: "The Press are always right. We must all believe what they tell us. They are the smart ones and would never mislead us..."
And no meteorite could possibly get through the clear top...it's Lexan and that is what bullet proof glass is made of....
And no meteorite could possibly get through the clear top...it's Lexan and that is what bullet proof glass is made of....
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St. Jude Donor '08-'09-'10-'11-'12
But in a Q&A about lightning in today's Chicago Tribune, it says:
"Am I safe during a thunderstorm if I'm in a car?"
"That depends on whether your car has a metal roof. A car's metal roof and sides protect occupants from lightning by directing the electricity through the car's frame and into the ground. You're not protected if you're in a convertible or on a motorcycle. Rubber tires don't offer protection."
"Am I safe during a thunderstorm if I'm in a car?"
"That depends on whether your car has a metal roof. A car's metal roof and sides protect occupants from lightning by directing the electricity through the car's frame and into the ground. You're not protected if you're in a convertible or on a motorcycle. Rubber tires don't offer protection."
Last edited by foremaw; Aug 5, 2011 at 05:26 AM.