# Spontaneous Combustion

## Main Question or Discussion Point

"SYDNEY (Reuters) - An Australian man built up a 40,000-volt charge of static electricity in his clothes as he walked, leaving a trail of scorched carpet and molten plastic and forcing firefighters to evacuate a building."
http://news.yahoo.com/s/nm/australia_electricity_dc [Broken]

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I was thinking the same thing when i read that. Could it be related to spontaneous combustion?

matthyaouw
Gold Member
PIT2 said:
Could it be related to spontaneous combustion?
In most spontaneous human combustion cases`(if that's what you're referring to), they talk about complete combustion of the person, with few or no burns on the surroundings. This seems to be the opposite.

Maybe this person made all the right moves. Is there anyway an electrically charged person can shock/burn himself?

Maybe by touching metal?

Gza
I found this kind of strange within the article:

"We tested his clothes with a static electricity field meter and measured a current of 40,000 volts, which is one step shy of spontaneous combustion, where his clothes would have self-ignited," Barton said.
since when did we start measuring current in volts?

LOL, good point!

CarlB
Homework Helper
I knew a librarian who sweared that a student set his self on fire in the library by static electricity. It was a very dry day, and he got shocked in the pants as he walked past a metal book case. He had a book of matches in the pants.

Carl

as far as this topic goes SC cant happen. its been explained away in every circumstance. what really happens is that the person burns very hot, but very slow. the body acts more like a wick and this explains why the surroundings aren't affected by such an "intense" fire. thats basically the long and short of it.

The whole story seems very fishy to me.

I'm a little surprised the figure of 40kV considered insanely high. Ever play with a 200kV van de graf? 500kV? Didn't exactly fry the general vicinity did it? Granted, 40kV is rather on the high side for building up static electricity just by scuffing your feet etc. As far as I understand, 2-5kV is pretty typical with 15kV or so starting to be considered pretty high though certainly not much danger unless you're in a no-spark area for some reason (gas station, fireworks factory, what not). Given the spark gaps, I'd say one of those *really* staticy days have to hit 40kV+ to do what they do.

LarrrSDonald said:
I'm a little surprised the figure of 40kV considered insanely high. Ever play with a 200kV van de graf? 500kV? Didn't exactly fry the general vicinity did it? Granted, 40kV is rather on the high side for building up static electricity just by scuffing your feet etc. As far as I understand, 2-5kV is pretty typical with 15kV or so starting to be considered pretty high though certainly not much danger unless you're in a no-spark area for some reason (gas station, fireworks factory, what not). Given the spark gaps, I'd say one of those *really* staticy days have to hit 40kV+ to do what they do.
I agree. I find it hard to believe a spark of that voltage could "fry" much of anything, although it is too high for a normal static buildup on a person from mere triboelectrification. That could be explained by the material of the mysterious shirt. Then, though, I have to wonder how a factory could manufacture this material without having all kinds of static problems to deal with in the looms and material handling machines. Could be they're already set up to handle that as a matter of course, I can't say, not knowing much about fabric manufacture.

Glad I'm not (at lease initially) ridiculed for saying this :-). Low-voltage (such as electronics) is my game, I rarely mess with the other stuff even though I hold it in the highest regard. It could well be that 40kV is rather out of range for normal buildup, I wouldn't know. I've been told that 15kV will bridge a 5mm or so gap under average (i.e. not excessivly humid 1kbar) conditions and having seen (as I'm sure we all have) significantly longer sparks without firing up the van de graf on those dry days when you just seem to shock anything grounded (which, in addition to building up more static, should also reduce the gaps if I'm not mistaken) ought to be higher. I've by no means reaseached it, it could well be that 40kV is way out of range (although it's danger have to be overhyped in this case, but then again we're talking "news" here which is usually an ancronym for "Not Even Within Seven magnitudes" in my book). It'd be interesting to hear what kind of spark gaps this would take, surely trivial for someone in the field even though it's beyond me.

My book on electrostatics says that 40kv can jump over an inch. The exact distance depends on the shape of the charged body. The more pointy it is, the further the spark can leap.

I don't see a carpet as a good sink, though.

The Wick Effect

HI, I was just wondering regarding spontaneous human combustion, if anyone would know any home experiments to test the wick effect or any means of testing it, on our own in a lab.
If anyone knows any information on this please email me at Jonathan.tan@csun.edu your help is greatly appreciated.

The way they tested it on two TV programs I saw was by starting a full pig carcass on fire. They figured this was the closest to a human body they could get hold of. I believe they wrapped a blanket around it and laid it on a conventional mattress indoors. The initial fire has to be intense enough to burn through the skin and expose the fat. From that point on, the fat supposedly liquifies little by little from the heat, seeps into the blanket and matress, which becomes the "wick", and does a slow, long burn from there.

In both cases they did this in some sort of expendible room. The smoke buildup pretty much ruins the interior of the room you use despite the fact it doesn't catch on fire. I don't think you'd be able to do this in a lab without permanently discoloring the ceiling and making it smell like smoke.

If I recall correctly they paid about $300-$400 dollars for the pig, and they had a fire truck from the fire department right there the whole time. I don't know how they arranged that.

In one case, the wick effect worked: the pig burned away leaving only traces. In the other case the pig went out well before it was burned up.

zoobyshoe said:
The whole story seems very fishy to me.
It was on the news on TV in australia. The guy was wearing some kind of material that can easily produce static electricity (forgot what it's called) and he was having an interview and I forgot the rest.

SGT
From the Skeptic Dictionary:
To prove that a human being might burn like a candle, Dr. John de Haan of the California Criminalistic Institute wrapped a dead pig in a blanket, poured a small amount of gasoline on the blanket, and ignited it. Even the bones were destroyed after five hours of continuous burning. The fat content of a pig is very similar to the fat content of a human being. The damage to the pig, according to Dr. De Haan "is exactly the same as that from supposed spontaneous human combustion."