electrical wiring turned heater

[satman]

I responded as a volunteer firefigher to a garage fire. The fire was so intense that there were no light weight ceiling joists left. Investigators said there were multiple starts due to the electrical wiring.

There was a 200 amp panel inside the garage with a 200 amp breaker on the meter panel outside. It had tripped! The investigator said the wiring in the building turned into a giant heater.

Was this a type of grounding issue?

Was this a result from the intense fire burning insulation from the wiring?

The building was stick frame , insulated with fiberglass and sheet rock. Roof metal and siding Hardie cement board.

Any thoughts?????

Fred

 

[peter d]

Re: electrical wiring turned heater

Electrical fires are caused by high impedance connections that have any number of source: loose screw terminals, wire nuts, or mechanical connections, pinched cords or wiring, poor grounding paths, etc.

So yes, it's a possibility that it was a grounding issue, but it's hard enough to find a source of a fire through a thorough investigation, let alone from a vague description that you provide.

 

[charlie b]

Re: electrical wiring turned heater

Fire investigators are sometimes too quick to lay the cause of a fire on the electrical system. It is often possible, and in your example it is certainly possible, that some other cause started the fire, and that the fire caused the electrical problems that were observed after the fact. For example, I am not at all surprised that the main breaker had tripped. That is its job. If a fire were to damage the insulation of all the wiring, that would result in a short circuit that should be high enough to trip the breaker.

 

[peteo]

Re: electrical wiring turned heater

Fire investigations are typically logged into federal forms, where information comes from. The answer is yes, electrical insulation does burn. The statement about multiple starts may have some viual evidence, when thermoplastic melts and allows sparking, and it's my guess that it turns into a gooey mess which burns hotter than softwood. Buried behind Hardibacker, it would be 'quite' troublesome to cool. The last (2002) code cycle included a requirement to remove abandoned low voltage wiring, specifically because it causes a 'fire burden.'

 

[haskindm]

Re: electrical wiring turned heater

The main breaker probably tripped due to the fire melting the insulation and ground faults and short circuits developed in the wiring. If what had caused the fire had tripped the main breaker, there would have been no power in the garage and the fire would have been prevented. The fact that the main breaker tripped is NOT evidence that the fire was electrical in nature, and may in fact argue that the electrical system reacted properly to the situation that was created by the fire.