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Old 07-04-2012, 05:56 PM   #31
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So, our house just suffered an electrical fire...


If there is some way to determine if the heat flow in the wire insulation was from outside in or from the inside out, uniformly heated from excessive current or local heating from a bad connection, you may have some clues as to the source, and some clues as to what was not the source.

Plastics/polymers people knowledgeable with PVC and whatnot would know this kind of thing.

Also, heating from electrical causes vs. heating from an open flame may leave a different signature on the insulation.
This is forensics in the extreme.

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Old 07-04-2012, 06:10 PM   #32
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So, our house just suffered an electrical fire...


The fire investigator could visually tell from the insulation on modern Romex if it burned from the inside out o from the outside in. He could also tell when insulation had baked off instead of burned. He didn't explain how he could tell, unfortunately.

He said arcing leaves pit marks, like an arc welder on iron and will usually heat wires enough to fuse them at that location as well.

He could also tell tons of things about the fire by the burn mark shapes and colors on the wood that were way above my head.
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Old 07-04-2012, 06:49 PM   #33
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So, our house just suffered an electrical fire...


Quote:
Originally Posted by biggles View Post
doesn't 220V out of a panel have to land into condensers,stoves with no break
Absolutely not.
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Old 07-05-2012, 10:54 AM   #34
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So, our house just suffered an electrical fire...


"He used the term pyratic... something (sorry). Also looks like its not the first time the beam has been burnt!"

The word is pyrolysis which causes the properties of the wood to be altered. Through repeated heating and cooling of the wood the ignition temperature of the wood becomes lower than normal which allows it to be ignited at lower than normal ignition temperatures. It often happens with low temperature heat over a long period of time. That alone isn't what causes the fire but when several pieces of the ignition sequence come together at just the right moment in time you can have ignition and a fire.
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Old 07-05-2012, 03:49 PM   #35
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So, our house just suffered an electrical fire...


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"He used the term pyratic... something (sorry). Also looks like its not the first time the beam has been burnt!"

The word is pyrolysis which causes the properties of the wood to be altered. Through repeated heating and cooling of the wood the ignition temperature of the wood becomes lower than normal which allows it to be ignited at lower than normal ignition temperatures. It often happens with low temperature heat over a long period of time. That alone isn't what causes the fire but when several pieces of the ignition sequence come together at just the right moment in time you can have ignition and a fire.
Very well explained. This happens very frequently around the stovepipe of a furnace when the clearance is not adequate and the wrong pipe is used. I friend of mine lost his house to this exact cause.

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