light fixture boxes burnt up

[jcoale]

had to give a bid on a fire damage house, noticed all the light boxes were burnt up- had caught on fire. this happened even where the fire had not even got to the sheetrock. the light boxes were the only thing that caught on fire ,nothing around them. the wood around all the boxes were burnt because of fire originating in the fixture box.
does somebody have a explaintion for this? maybe a bonding or grouding issue?

 

[Dennis Alwon]

had to give a bid on a fire damage house, noticed all the light boxes were burnt up- had caught on fire. this happened even where the fire had not even got to the sheetrock. the light boxes were the only thing that caught on fire ,nothing around them. the wood around all the boxes were burnt because of fire originating in the fixture box.
does somebody have a explaintion for this? maybe a bonding or grouding issue?

I am not sure what is going on there but I will assure you that not every lighting outlet caught fire at the same time. The blackness may be smoke damage from the actual fire since there is an opening at that point or the fixtures all have been slowly blackeneing the wires over time due to excessive heat from oversized bulbs.

 

[jcoale]

the rafters and joist were not smoke damage, they were acually burnt just like wood on a campfire. maybe that was a point where air was allowing for combustion because of space around sheetrock. dont no never seen this before.

 

[cowboyjwc]

What we call smoke is actually hot gas. That gas can be hot enough to ignite combustable material. My guess would be that the holes were cut to big around the light boxes? Also being up high like they are they might have trapped the gas inside and then the wire insulation ignited.

I always try to talk to the fire investigator when I see something like that so that I get a good explaination so that I'll know the next time I see it or so I can explain why there is a code section limiting the space allowed around boxes.

 

[Sierrasparky]

Sound like hot gases burning the area. That's why we need to fire tape poperly and install fire Caulk when required. I've seen it before.
A fire in the attic of a wall the gases leak where ver they can. All the bad drywall taping shows when you have a fire like that.

 

[360Youth]

the rafters and joist were not smoke damage, they were acually burnt just like wood on a campfire. maybe that was a point where air was allowing for combustion because of space around sheetrock. dont no never seen this before.

That would be my guess. The draft of air around the box fanned the flames.