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Author Topic: Lightening and cows  (Read 6559 times)

Scott Helmke

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Re: Lightening and cows
« Reply #10 on: May 31, 2016, 10:13:41 am »

If caught outdoors in a storm away from shelter, I'd imagine the best tactic would be to crouch in a fetal posture with your feet as close together as possible, away from trees. That would reduce voltage gradients across the body.

I've been told, by serious camping people, that you should have your feet wide apart. Doesn't make any sense to me, though - I'd think you're correct about keeping feet together.
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Nathan Riddle

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Re: Lightening and cows
« Reply #11 on: May 31, 2016, 11:44:48 am »

I saw this a few weeks ago, thought it was a very good guide in my humble opinion.

http://www.artofmanliness.com/2014/04/24/how-to-survive-a-lightning-strike-an-illustrated-guide/

I think the feet wide apart is pretty silly, but I haven't heard the case for/against it so I'm not really sure what to think of it beyond the surface of the statement.
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Mike Sokol

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Re: Lightening and cows
« Reply #12 on: May 31, 2016, 12:16:50 pm »

I've been told, by serious camping people, that you should have your feet wide apart. Doesn't make any sense to me, though - I'd think you're correct about keeping feet together.
That's incorrect. You need to keep your feet together to minimize any gradient voltage induced shock. I have an entire forum dedicated to training camping people about electricity, and the old wives tales I hear are crazy, and sometimes very dangerous.
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Mike Sokol
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Doug Fowler

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Re: Lightening and cows
« Reply #13 on: May 31, 2016, 01:09:11 pm »

That's incorrect. You need to keep your feet together to minimize any gradient voltage induced shock. I have an entire forum dedicated to training camping people about electricity, and the old wives tales I hear are crazy, and sometimes very dangerous.

What about a FOH platform skinned with vinyl and aluminum?  Faraday shield or not?
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John Roberts {JR}

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Re: Lightening and cows
« Reply #14 on: May 31, 2016, 03:12:38 pm »

What about a FOH platform skinned with vinyl and aluminum?  Faraday shield or not?
To mitigate lighting hazards a lightning rod mounted to a high spot can discharge the local build up of charge that can attract lightning so basically prevent lightning, and if not completely successful, steer it harmlessly away from humans, while the current from a lightning down strike will vaporize the typical lightning rod ground wire, so try to run it in a shortest straight path. The lightning rod top needs to have a sharp pointy end, or multiple points to make it easier for electrons to jump off (or on?) to discharge the local field.
=====

Lightning routinely strikes metal aircraft without harming the passengers inside so being inside a metal can might work, but general advice is to avoid strong electrical conductors.

JR
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Dave Garoutte

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Re: Lightening and cows
« Reply #15 on: May 31, 2016, 08:45:41 pm »

What about a FOH platform skinned with vinyl and aluminum?  Faraday shield or not?
You need to be completely enclosed to be protected.
Electrons repel each other, so the charge is literally on the outside surface of the farraday cage (car, plane, etc).
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Stephen Swaffer

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Re: Lightening and cows
« Reply #16 on: May 31, 2016, 10:22:21 pm »

What about a FOH platform skinned with vinyl and aluminum?  Faraday shield or not?

I wouldn't count on an aluminum skin-a substantial framework that you are inside of would be more effective.  As light as aluminum or steel panels are these days, I would expect them to melt or vaporize instantly.

Several years ago I was doing FOH under a tent with 20 foot tall, 5" diameter aluminum main poles.  I wondered if they would be an effective lightning rod-and whether it made under the tent safer or just a target.  Thankfully, I never learned the answer.
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Jonathan Johnson

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Re: Lightening and cows
« Reply #17 on: June 01, 2016, 12:55:24 am »

I think the feet wide apart is pretty silly, but I haven't heard the case for/against it so I'm not really sure what to think of it beyond the surface of the statement.

As Mike alluded to, the concern is voltage gradients.

When lightning strikes nearby, the electricity is discharged into the ground and current radiates out from the point of strike. The further you move away from the point of strike, the greater the voltage differential between the point of strike and the measured point. Two points close together (i.e., your feet next to each other) in the vicinity of the strike will have a lower voltage differential; two points far apart (i.e., your feet in a wide stance) have a higher voltage differential.

As a general rule, your body is a better conductor of electricity than soil is. So when you have a high voltage differential -- when your stance is wide -- there is the potential for high current flowing through the body*, causing injury. By keeping your feet close to each other, you minimize the voltage differential and, therefore, the potential current through your body.

Some of the old wives' tales may be based on the idea of not being the tallest object in the area and minimizing the electric charge in your body. If this were the only concern, laying spread eagle on the ground would be best. But laying spread eagle also maximizes the voltage differential your body will experience with nearby strikes. Since a direct strike to the body is much, much less likely than a nearby strike, a crouch with closely planted feet is the safest compromise. Your height is minimized, making you a less likely target, and voltage differential between parts of your body is minimized to reduce the potential current through your body.

*It should be noted that the maxim "electricity takes the path of least resistance" is very misleading. Electricity takes ALL conductive paths, though the greatest current will be through the path of least resistance. Even if the soil has a lower resistance than your body, the voltage potential in a lighting strike is so high that the potential current through your body can still be deadly.
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Mike Sokol

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Re: Lightening and cows
« Reply #18 on: June 01, 2016, 06:47:37 am »

I wouldn't count on an aluminum skin-a substantial framework that you are inside of would be more effective.  As light as aluminum or steel panels are these days, I would expect them to melt or vaporize instantly.

Several years ago I was doing FOH under a tent with 20 foot tall, 5" diameter aluminum main poles.  I wondered if they would be an effective lightning rod-and whether it made under the tent safer or just a target.  Thankfully, I never learned the answer.
During my conversations with NOAA about lighting safety, we discussed the fact that tents are perhaps the worst place to be in during a lighting storm. The metal support poles are tall enough to make them a target for a lighting strike, but don't provide real Faraday Cage protection. There's been a number of Boy Scout lighting strike incidents where exactly that happened. The Leaders took the kids into a tent during a lightning storm where they huddled on the ground. Lightning hit the ground very close to the tent, and many of the kids suffered high-voltage damage to their bodies and nervous systems.

Non-Convertable cars have been demonstrated to be safe for occupents even with a direct hit from lightning. But the cars generally don't do very well with the on-board computers fried and the tires over-pressured from the lighting that jumped the gap from the wheels to the ground INSIDE of the tires. I don't know where I saw it, but apparently that's a problem with big construction equipment that's been hit by lightning. You've seen those enormous earth movers with tires taller than you. Once they've been over-pressured by a lightning strike they can sit there like a time-bomb for days. So the next person who moves them can be in the blast zone of those tires exploding due to weakened structure. I'll see if I can find any pictures and post them later..

I think the consensus is to get the heck out of the tent and into a substantial building (or at least the truck) if lightning gets close. 
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Mike Sokol
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Scott Helmke

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Re: Lightening and cows
« Reply #19 on: June 01, 2016, 08:16:23 am »

What would be something that a backpacker could carry to reduce the risk of injury? For the backcountry types it's either stay in the tent, or go outside and risk hypothermia from getting soaked with cold rain.
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Re: Lightening and cows
« Reply #19 on: June 01, 2016, 08:16:23 am »


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