Coiled Extension Cord Cause Fire?

[Grollor33]

Hey all,

A friend of a friend's house burned down last week. The cause given to them (from who?) is that a coiled extension cord was the root cause.

Now i^2 r being what it is, I can understand that a cord passing current will heat up - even if not to "overload". And although I'm a sparky, I can see how not allowing the heat move away from the cord (by coiling it, perhaps) could cause excessive heating resulting in fire. AND I can even understand (although with a slippery grip) inductive heating of a coiled wire. But...

Their cord was not connected to a load. Simply coiled and sitting there - although still plugged into the outlet.

So, what I can't understand is: if there was no load and therefore no current, how could this coil of conductor be the culprit? I can almost fathom an effect if were were talking about incredibly high frequency (though I'd be reaching way out of my limited intellectual comfort zone).

Can someone explain what I'm missing, here?

 

[mcgyvr]

You simply missing the fact that however determined that to be the cause is an idiot and is incorrect.
If there was no load on the cord, there is no voltage/current flow, and no heating..no heat = no chance for fire. Not to mention that even a fully loaded UL approved/listed cord (loaded to it's max. rated ampacity) does not generate enough heat though its insulation to start a fire.

 

[DRWeig]

I gotta vote with mcgyvr if the facts are as stated.

Even if there were a load, you don't get inductive heating from a coiled cord or they wouldn't sell them to us in lengths longer than a foot or so. The supply and return are in the same cord, there's no net magnetic field. In this case, with no load at all, there's no current.

Now, if the cord were laying there plugged in, and the cat chewed away the insulation, and the dog dragged his metal water bowl over, and...

Ah, but all the inspectors ever get to see are charred remains.

Good on ya,

Goober Dave

 

[cranky108]

Not to start anything, but given the warnings on the cords package, why would you leave a cord pluged in without anything attached to it?

Most cords that I have seen will say for temperary use only.

So with that in mind, an inspector might believe the cord had to be connected to something. Possibility something to large for the cord.

They really don't know what started the fire. They probally have a good idea of where it started. So they jumped on a conclusion.

 

[Skogsgurra]

This is another wide-spread urban myth.

It is a fact that a coiled extension cord, when carrying current, can overheat. But most have a built-in thermal protection that prevents this from happening. And not loaded will, of course, not overheat.

A warning sign is that it was "A friend of a friend" to which it happened. he "FOF" is a houshold expression in urban myth world.

Gunnar Englund

http://www.gke.org

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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

 

[LionelHutz]

Maybe the cord had bad insulation.

Maybe the female plug on the open end was worn out and failed. I have been told before that a well used cord can arc in the female plug, to the point it was caught starting a car cover on fire.

If you have one of the cords in those plastic winders and try to use it for a significant load without unwinding it all you will melt the insulation.

 

[Grollor33]

The FOF to which I was referring:

http://www.pittsburghlive.com/x/pittsburghtrib/news/westmoreland/s_633742.html

...apparently this happened on an outside porch...perhaps a slightly thickened plot...

 

[mcgyvr]

I'd bet on the propane tank anyday...flopping hose leaking propane..hitting metal causing spark..propane igniting... burning down house...
If the fire was already started and enough to burn a hole in the propane line causing a leak, I doubt that the neighbors would hear the hissing of propane without noticing the flames shooting out of it. As soon as that fire burnt a hole in the line the propane would ignite.

 

[MacGyverS2000]

Inductive heating at 60Hz from a line cord? Not likely...

Bad insulation? Likely...

Dan - Owner

http://www.Hi-TecDesigns.com

 

[ScottyUK]

Fused plugs... oh, that's UK-only: everyone else knows better than us.


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If we learn from our mistakes I'm getting a great education!

 

[IRstuff]

Sure, but frayed, or otherwise damaged, cords are quite common. These things shorting out could certainly start a small fire that gets larger.

TTFN

FAQ731-376

 

[OperaHouse]

An plugged in extension cord will be flagged on any routine fire inspection of a commercial building. Given that there was a fire, the extension cord melted and then shorted. That would have given enough evidence to cite the cord. When they can't find a definite cause it is always easy to say it was electrical.

 

[EEJaime]

Let me see, four teenagers home alone. A gas grill with a disconnected hose. One teenager goes outside to "investigate" an "explosion" that he "thought he heard" and the neighbors saw the propane hose swinging wildly back and forth hissing gas.

Sounds like the fire officials did not do much of an investigation or ask enough questions of the "children".
EEJaime