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Statically Charged Man Ignites Office
Call Me Black Cloud writes "And you think your coworker with BO is annoying? In this story carried by Reuters, a man wearing a nylon jacket over a wool shirt built up such a static charge that he left a trail of scorched carpet and melted plastic in his wake. After he melted plastic in his car he sought help from firefighters called to the scene, who measured his static field at 40,000 volts." Obviously, despite the fact that this is carried by Reuters, you should take some of the 'facts' presented here with some NaCl.
40,000 volts is only enough to generate a few microamps over a small gap in the air. Air has a huge resistance. There's no way 40,000 volts could cause that much damage. From a quick internet search, it appears even a simple van de graff generator would create over 75,000 volts, and that's fairly harmless.
The reports are also inconsistent. The AP is saying it was 30kV, Reuters is saying 40kV.
I have a MSEE and feel like feeding the news trolls.
I put more faith in the Loch Ness Monster than this crap. Shame to see it actually in the "real" news.
1. Current is measured in amps, not volts.
2. WTF is the FIRE department doing with a volt/amp meter? Most (cheap) volt meters don't measure past 1000 volts AC/DC.
3. One or two squirts of water from a spray bottle would have completely discharged the jacket -- assuming somehow the natural humidity didn't!
4. and of course the jacket could never have built up such powerful charges as to melt and burn materials...
5. Seems unlikely that static electricity would be likely to flow *through* plastic, a *non-conductor*.
6. For the jacket to "continue" to give off an electrical current, several things must be happening:
a) There must be somewhere for it to go.
b) There must be something actively ionizing the electronics in the jacket. This requires force, external electricity, etc.
c) The "destination" of the current must also remain oppositely ionized. (Otherwise some current would flow and then things would be balanced). Maintaining the ionization of the "path to the destination" would also require external force, electricity, etc.
Hey, it's Carpeted Man from The Tick!s hcarp.html
http://www.cs.rose-hulman.edu/~stinerkt/tickdocs/
If it's a hoax, it's fooled a lot of people.
Why would anyone engrave "Elbereth"?
http://the.standard.net.au/articles/2005/09/16/112 6750111141.html
What?
40kV isn't hard to build up. In fact, you can safely play with hundreds of kV, and make some really nice sparks. The 'starting things on fire' number you're looking for is power. And energy. You need to be able to transfer enough energy into an object that it will reach its combustion temperature, and you need to be quick enough at it that the object doesn't shed the energy to nearby objects in the meantime. It takes a lot of energy (as compared to the energy content in your average static 'zap') to set carpet fibers aflame, or even melt them.
Not to say that it didn't happen, of course. It's just not well-reported, and is clearly not terribly common.
High-speed Road Trip (18.000KPH)
"We tested his clothes with a static electricity field meter and measured a current of 40,000 volts..."
;)
Last time I checked, the unit for current is Ampers, not Volts. Volts measure the potential for current, not current itself. Besides, a static feild has no current... because it's static.
Anyway, it's too bad he doesn't work on computers, I'd love to see his anti-static bracelet. I think #00 gauge welding cable would handle it.
This sig rocks the casbah.
A few other points:
1. Clothes (or anything else for that matter) does not "spontaneously combust" because they are charged to a particular voltage. It's only the discharge (i.e. flow of current) that can ignite something (see #2).
2. Combustion can occur from a spark (which can happen at nearly any voltage, but let's just say 1,000 volts as a reasonable minimum), but it would be highly unlikely to ignite ANYTHING except gas or other flammable fumes.
I've passed multiple 50,000 volt simulated discharges through dry paper (yes, I was playing with a piece of test equipment meant to simulate static discharges at various voltages) and didn't get so much as a scorch mark. To say that conditions would have to be "perfect" is an understatement. Any material that you would find in an office building could not be ignited by static discharge from a human, there simply is not enough energy.
BTW, people can discharge as much as 5,000 volts and not notice it. Discharging 40,000 will make you stand up and take notice, big time! 50,000 is quite painful.
Bullshit. Electric field strength is measured in Newtons per Coulomb. One Volt is one Joule per Coulomb. Since a Newton is completely different from a Joule, you can't measure electric field strength in Volts. Anybody who tells you otherwise is wrong, and needs to go back to highschool.
They werent exaggerating the burn marks, I saw this on TV and they showed the burn marks. While this may not have happened exactly the way the article describes it its pretty close. In Australia it can get pretty dry and as long as he dident touch any conductive surfeces it is very possible for staic to build up like this, with his coat acting like a battery and his shoes insulationg him from discharge the static would have built up until it was strong enough to make it past the rubber in the shoe. Also I doubt this story is fake because when I saw it on TV they had fire dept, the man in question and his job interviewer there although its not like they could get a decent scientist to investigate at such short notice so some of there "facts" are probably wrong.
A Van De Graaf generator is basically a band of insulating material being rotated in a tower with some means of transferring a charge to it. There are relatively cheap desktop and home models that'll produce nearly half a million volts. Schools use such devices all the time, so if the fireman hasn't seem a voltage that high, he skipped classes.
Having said that, early atom-smashers used Van De Graaf generators only capable of producing five million or so volts. It seems reasonable to suspect something will burn before it is blasted out of existence. So, somewhere between 400,000 volts and 5,000,000 volts, you might be able to ignite something.
However, here we get a problem. You can't just carry around half a million volts and not notice it. Your hair tends to stand on end, for a start. ANYTHING metal - even a doorknob - will cause a discharge to occur. Getting into his car certainly would have - even if the car were carbin-fiber, the key would be metal and the distance short enough for an arc to occur.
There's also the problem of where you lodge a charge that great. A capacitor is basically two electrostatic devices with an insulator between them. In this case, the insulator would be the shoes, and the electrostatic device the person. I'll assume there are enough nails holding the carpet down to act as the other electrostatic device.
But what is the capacitance of a person? The figure I've been able to get with a Google search is an average of 204 pF with a typical range of 95 to 398 pF. (It varies according to height and weight, so a seven-foot sumo wrestler might have a higher capacitance than this range shows.)
In other words, not really what you'd need to carry half a million volts around. The jacket would have carried more, but unless it was made of Tantallum or some other material with very high capacitance, I doubt you'd be able to store enough charge to start setting things on fire.
In other words, there is nothing credible about the story. The voltages are abnormally low for a static device and way too low to actually do any fire damage, there's nowhere a higher charge could have been stored and there would have been too many points at which positively violent arcing would have occurred if it had been stored.
It's a small world and it smells funny; I'd buy another if it wasn't for the money; Take back what I paid (SoM)
See the show. The researchers reproduced SHC with a rather large pig, possibly making it SPC (Spontaneous Porcine Combustion) or RIPC (Researcher Induced Porcine Combustion). Pigs don't normally wear clothes but this one was draped for the occasion. Only parts of the body burn because only parts are covered with a wick (cloth). It burns without damaging nearby objects because it burns with a very low flame. Convection disperses the heat throughout the room. If you look at reports of SHC you'll find that there is always a source of combustion involved but it's always dismissed because the whole place didn't burn down. The experiment even resulted in bones that powdered at a touch, another characteristic of SHC. As it happens, horse shit has nothing whatsoever to do with it.
Look at the bright side: there's always seppuku.
They did several variations on the static electricity theme already, the two most famous probably being the PVC pipe (in which Jamie built a van de Graaf generator) and the cell phone sparking a gas station fire myths.
"We are Microsoft. You shall be assimilated. Competition is futile."
Those that think this is a hoax better think again. There were some brief interviews with very sober looking office workers (the guy was there for a job interview) as well as the fire brigade officer that attended. There were obvious, though small, scorch marks on the carpet.
He had a synthetic (nylon??) jacket over a woolen jumper apparently. Assuming it was a day with 0% humidity it is all quite possible
Just to amplify your comment, most (cheap) volt meters have too low a resistance to measure potential on a tiny capacitor, such as a human body (~250 pF), because the voltmeter would discharge the capacitor before it could get a reading.
Someone else replied about measuring downed power lines, but that would: (a) not require a voltmeter to read over 1000 volts and (b) not require an ultra-high-impedance static-charge electrometer.
BTW, let's do the numbers: 40,000 volts across a 250 pF capacitor would have potential energy of 1/2 CV^2 = 0.2 Joules. If you think that 0.2 Joules is enough energy to melt macroscopic amounts of plastic or burn carpet, much less almost enough to incinerate a human body, I have a hot investment tip for you.
Do a google search for "electrostatic voltmeter". It's an optional mode for voltmeters to detect high voltages. There's at least one company which makes such a device Multi Function Digital Voltmeter which goes up to 500 KiloVolts.
Vintage computer adverts: http://www.vintageadbrowser.com/computers-and-software-ads
The Original article is much clearer. They called an electrician.
Reuters just made some shit up and made the story look even more like bullshit than it already was.
Even in cases of unexplained Spontaneous Combustion, it's probably not really spontaneous. It's just that nobody really knows what the ignition source is, and Spontaneous Human Combustion just sounds so much cooler than Human Combustion by Unknown Ignition Source.
GreyPoopon
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Why is it I can write insightful comments but can't come up with a clever signature?
At the risk of going offtopic (and spoiling most users)...
The gas station fire myth (episode 2) was based on the myth that using a cellular phone at a gas station was dangerous because it could create a spark that would ignite the gasoline fumes. Jamie and Adam built a test rig that would test this and other potential ignition sources (among these a pantyhose-based charge generator and a lighter), but they found that using a spark to light gas fumes is easier said than done.
The PVC pipe myth starts as follows: "A construction worker finds a length of PVC pipe, but there's some paint on it he'd like to remove. He sandblasts the pipe, but in the process the pipe collects a large enough charge to literally act as a lightning gun, shocking the hapless worker." After a few frustrating runs with the PVC pipe, Jamie built a van de Graaf generator out of a pipe and other items in his shop, while Adam tried to turn the PVC pipe into a giant capacitor.
"We are Microsoft. You shall be assimilated. Competition is futile."