News Story Static Electricity

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jollyrgr
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News Story Static Electricity

Post by jollyrgr » Fri Sep 16, 2005 3:49 pm

This has got to be fake.....<p>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. <p>Frank Clewer, who was wearing a woolen shirt and a synthetic nylon jacket, was oblivious to the growing electrical current that was building up as his clothes rubbed together.<p>When he walked into a building in the country town of Warrnambool in the southern state of Victoria Thursday, the electrical charge ignited the carpet.<p>"It sounded almost like a firecracker," Clewer told Australian radio Friday.<p>"Within about five minutes, the carpet started to erupt."<p>Employees, unsure of the cause of the mysterious burning smell, telephoned firefighters who evacuated the building.<p>"There were several scorch marks in the carpet, and we could hear a cracking noise -- a bit like a whip -- both inside and outside the building," said fire official Henry Barton.<p>Firefighters cut electricity to the building thinking the burns might have been caused by a power surge.<p>Clewer, who after leaving the building discovered he had scorched a piece of plastic on the floor of his car, returned to seek help from the firefighters.<p>"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.<p>"I've been firefighting for over 35 years and I've never come across anything like this," he said.<p>Firefighters took possession of Clewer's jacket and stored it in the courtyard of the fire station, where it continued to give off a strong electrical current.<p>David Gosden, a senior lecturer in electrical engineering at Sydney University, told Reuters that for a static electricity charge to ignite a carpet, conditions had to be perfect.<p>"Static electricity is a similar mechanism to lightning, where you have clouds rubbing together and then a spark generated by very dry air above them," said Gosden.
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Gorgon
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Re: News Story Static Electricity

Post by Gorgon » Fri Sep 16, 2005 4:27 pm

<blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr>Originally posted by Jolly Roger:
Firefighters took possession of Clewer's jacket and stored it in the courtyard of the fire station, where it continued to give off a strong electrical current.
<hr></blockquote><p>Why didn't they connect this to the electric grid? Converted 40kV and 'strong current' makes a lot of power! :D <p>TOK ;)
Gorgon the Caretaker - Character in a childrens TV-show from 1968. ;)

Robert Reed
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Re: News Story Static Electricity

Post by Robert Reed » Fri Sep 16, 2005 5:11 pm

If his clothes were at 40KV, his in contact body would be too. With a static discharge of those proportions, I think rather than calling the fire dept. ,someone should have to call an ambulance for the poor fellow.

terri
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Re: News Story Static Electricity

Post by terri » Sat Sep 17, 2005 11:14 am

In the spirit of hunting down and killing variables, and as a mental excercise:<p>One of the problems science faces is that so many scientists tend to dismiss that which they cannot explain. William James had some comments about this over a century ago, but I'll let that go for now.<p>So let's approach this, not from a "naysayer" point of view, but from a "yaysayer's" viewpoint. What would be necessary for this to actually happen?<p>(It should be noted at the outset that a report which uses the phrase, "a current of 40,000 volts," is automatically suspect in the first place.)<p>Okay, we know that friction can develop some enormous charges --viz the various machines to generate high voltages --the Wimshorst(sp?) and Van de Graff(sp?) machines, for example. And what is lightning but release of charges built up by air movements?<p>We have, in this case, a woolen shirt and a synthetic jacket rubbing against each other, which, in a dry climate, would in fact generate static --remember the "hard rubber comb" rubbed on a piece of wool experiment which generated enough charge to attract small pieces of paper?<p>Okay, so if a charge is generated between the wool and the jacket, where would the charges go? Half the charge would remain on the synthetic jacket, which is an insulator, half on the wool shirt. The shirt charges would be transferred to the wearer's body. Let's say the charge between the jacket and the wool (or wearer's body) was about 40kV, for the sake of a number. That means that the wearer's body would have a charge, with respect to the ground (earth) of 20kV.<p>So a charge-to-ground on the wearer's body would exist, being about half the total voltage generated.<p>Okay, so where could this charge go? It could leak back to the jacket (or suddenly discharge to the jacket if the potential got high enough, as with the crackling "static cling" of removing an item of clothing) or to ground.<p>Okay, so what is necessary for the charge to go to ground, i.e., through the carpet to ground, with sufficient power to ignite or char the carpet? (This term is used in its technical/conceptual sense of "rate of dissipation of energy," without quantification, so let's not get into another "foot-pound-foot" discussion, OK?) <p>It is unstated what kind of footgear was worn, so there are two extreme cases: 1. totally conductive footwear; and 2. "perfectly" insulated footwear. Let us assume the footwear is somewhere in the middle, that is, "conductive enough to allow the charges to escape at some point," but also "insulating enough for the charge to build up in the first place." Okay, that's out of the way. We have defined the "footgear conductivity" variable as "having that value which is necessary for the reported phenomenon to occur." Again, we are taking the "yaysayer's" viewpoint herein.<p>In order for there to be sufficient power to generate the thermal effects, that is, the charring of the carpet, there needs to be a rapid escape route, which infers that either the carpet itself or the underlying flooring has to be pretty conductive.<p>The next question is, can enough energy be stored in the body capacitance of the woolen shirt wearer such that the reported phenomenon can occur? Bear in mind that of the above-hypothesized 40 kV between the shirt and the jacket, only half would appear between the body of the wearer and ground. Now it's a question of body capacitance. With the reported "40kV," this means that only half, or 20kV would appear between the wearer and ground, or earth, for you Aussie readers.<p>Now, as a matter of experiment, I have ignited "flash paper," which is nitrated tissue paper (available in magical equipment stores,) by placing it on a well-grounded surface and building a rather high charge on my body (by walking across the floor in some particularly "static-generating" slippers) and bringing a metal house key to the paper. This experiment does not work with either black or smokeless gunpowder --apparently the graphite coating on the powder grains conducts the spark around the actual propellant grains. Even with the flash paper, one has to generate one heck of a hefty fat spark (3/8 inch) to ignite it.<p>However, this was done in winter in the high dry clime of Colorado, where the relative humidity frequently drops to 15% or less --at this moment it is 17%, according to my hygrometer.<p>And, according to the report, Mr. Clever at one point left a trail of charred carpeting behind him.<p>I submit that this carpeting must have been dangerously inflammable or otherwise chemically unstable for this to occur. After all, it is not nitrated. We do know that static can ignite gasoline vapors, as is well-documented, but the carpeting is neither nitrated or in a vapor state.<p>My conclusion would be, even taking the "yaysayer" viewpoint, is that only an extraordinary concatenation of circumstances would bring this phenomenon barely into the realm of possibility. And that the reporter or the characters involved hyperbolized some actual moderately-unusual events for the sake of a good story.<p>Truth as reported P =< 0.000001, in my opinion.<p>Personally, I think maybe somebody happened to drop a lit cigarette somewhere they shouldn't have been smoking, which resulted in the call to the Fire Department.<p>More comments? Please, let's hear them.<p>[ September 17, 2005: Message edited by: terri ]</p>
terri wd0edw

Will
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Re: News Story Static Electricity

Post by Will » Sat Sep 17, 2005 3:00 pm

Then Aussies always were a hot-assed bunch - Does anyone think that this makes a case for making all carpets intrinsically safe ? (Or just explosion proof ?)
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