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Death by Capacitor vs. Lightning

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cduma

Mon Feb 09 2009, 01:00AM

Registered Member #1822 Joined: Fri Nov 21 2008, 08:04PM
Location:
Posts: 300

Why Is the survival rate for Lightning strike victims higher than those who get hit by a high voltage capacitor. Lets call high voltage 10kv. Why do capacitor victims not require immediate Kidney Dialisys machine to survive more than a day or two but, lightning victims do.

Backyard Skunkworks

Mon Feb 09 2009, 01:57AM

Registered Member #1262 Joined: Fri Jan 25 2008, 05:22AM
Location: Maryland, USA
Posts: 451

I'm not quite sure what your talking about, but I should point that getting hit by lightning IS getting shocked by a high voltage capacitor. I'm also not quite sure where your getting your stats from, although I do remember that something like 75% of people who get hit by lightning do survive. And someone correct me if I'm wrong, but I don't think there is anything special about getting hit by lightning that requires kidney dialysis.

Chris Russell

Mon Feb 09 2009, 02:21AM

... not Russel!
Registered Member #1 Joined: Thu Jan 26 2006, 12:18AM
Location: Tempe, Arizona
Posts: 1052

A quick Googling around indicates that lightning strike victims can suffer from myoglobulinuria, presumably due to rhabdomyolysis -- damage to muscle tissue. All the good articles about this are behind various paywalls, but from what I can gather, it works like this: If a lightning strike does massive damage to the muscles, myoglobulin is released into the bloodstream in large amounts by the damaged tissue. This can cause kidney failure if left untreated, as the kidneys can only handle so much myoglobulin at once. It's not unique to lightning strikes; any sufficiently large amount of trauma can cause this condition. I see no reason why a large capacitor shock, or any sufficiently powerful shock, couldn't cause myoglobulinuria.

As to the higher survival rates, I'd guess that the shorter lightning pulse leads to increased skin effect, meaning lethal currents are less likely to reach the heart as compared to a capacitor hit, which has a much much longer pulse time in most cases.

LithiumLord

Mon Feb 09 2009, 02:31AM

Registered Member #1739 Joined: Fri Oct 03 2008, 10:05AM
Location: Moscow, Russia
Posts: 261

As far as many refer the step voltage shock, the shockwave effect and getting shocked by a leader or just the static charge induced by a huge dv/dt as a lightning strike I see the reason why ;) Otherwise, if considering "getting hit by a lightning" an actual headshot, I bet there's not much chance to survive, at least not higher then the one of one's corpse to remain in an "SFW-pic-friendly" condition that is really slim to nothing ;)

Nik

Mon Feb 09 2009, 03:24AM

Registered Member #53 Joined: Thu Feb 09 2006, 04:31AM
Location: Ontario, Canada
Posts: 638

Shocks from 240V or higher you should go to the hospital as soon as possible. In trade school they drill it into our heads over and over, the reason being that a shock from 240 or higher can cause the blood in you to burn a little forming a clot that can grow and lodge some where important killing you hours later. That may be one of the reasons why you have to be put on a dialysis machine to remove any burned bits from you.

As for why lightning hits seem to be more survivable then a capacitor shock, could be the path both shocks take and the duration. In a capacitor it will probably be from your hand to your other hand or another limb and lasts a significant amount of time if it is a big enough capacitor at a "low" 1-2kv voltage. Lightning on the other hand will be going head to toes lasting (wikipedia) ~30uS, perhaps having the current spread across your whole body cross section instead of between two limbs help stop the much higher current from killing you.

LithiumLord

Mon Feb 09 2009, 10:42AM

Registered Member #1739 Joined: Fri Oct 03 2008, 10:05AM
Location: Moscow, Russia
Posts: 261

Well, this is getting a bit of paranoic, don't you think? ;) In fact you are mixing the two different effects - getting "hit", when the shock just makes the screaming you jump aside and land flat on your back, and getting "attracted", when the muscular shock makes you unwillingly hold the object under voltage with a strong grasp. The first effect has merely any lasting consequences as the exposure times are usually very short to cause such a high heating of the tissues and liquids (speaking of the voltages below ~500vac - as voltages referred as "high", eg. 1+Kv, are those that definitely cause some lasting effects, including burns, neural damage and blood damage). Getting "attracted", as some people call it, is another thing - the exposure times are high enough to cause the thermal damage as well as the neural one and a bad hit on the muscular tissue. However don't forget that RF currents, like those of Tesla coils, have pretty the same effects - even if you can't feel the hit itself.

As for the lightning, only the energy counts - and it is enough no matter what part of a man's volume it needs to heat up. Even the shockwave itself is enough to crack a cinder block in two (a guy who worked with the lightning protection test system once told me how someone left a cookie on the test platform. When the system was a press of a button from being engaged, an unlucky crow came down for it's breakfast, guess what happened. With a man it will not do such a painting job, but I bet there's not much chance to live through that). Actually, this discussion feels pointless unless we have a straight statistic on those hit with caps' charge (those exposed vs those who survived/died at the specific cap bank energy) and same for the lightning hits (head-on hit, same two values). Or it may get funny the other way - one man ended up drilling a hammer drill up his forhead to travel half of his skull - and lived. Doesn't this mean that it's 100% safe to drill your head with a hammer drill? ;)

PS

If you'll take a closer look, NONE of those here had a direct hit ;) (only leaders and step charge hits)

Shaun

Mon Feb 09 2009, 05:27PM

Registered Member #690 Joined: Tue May 08 2007, 03:47AM
Location: New Jersey, USA
Posts: 616

LithiumLord wrote ...

PS

If you'll take a closer look, NONE of those here had a direct hit ;) (only leaders and step charge hits)

You could always get lucky and wind up with ESP, like "Missy".

big5824

Mon Feb 09 2009, 06:12PM

Registered Member #1687 Joined: Tue Sept 09 2008, 08:47PM
Location: UK, Darlington
Posts: 240

just out of interest, does anybody know how much capacitance an average storm cloud has?

Also, I thought the kidney dialysis was because the DC shock can electrolyse some bodily fluids, releasing harmful chemicals.

Conundrum

Mon Feb 09 2009, 07:20PM

Registered Member #96 Joined: Thu Feb 09 2006, 05:37PM
Location: CI, Earth
Posts: 4062

Wasn't aware of this side effect...

That said, I know of someone who was struck by lightning, and they didn't mention anything about dialysis. maybe it only occurs a percentage of the time.

-A

Bored Chemist

Mon Feb 09 2009, 09:27PM

Registered Member #193 Joined: Fri Feb 17 2006, 07:04AM
Location: sheffield
Posts: 1022

If your capacitor stored something like 100MJ to 500MJ at 10KV it would do much the same to you as a thunderbolt.

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