czars
Czars
- Location
- West Melbourne, FL
- Occupation
- Florida Certified Electrical Contractor
For what it's worth, a CFL bulb failed in my attic and set the attic on fire. Not good.
The forensic fire investigator spent 6 hours investigating the cause of the fire. Here is the situation.
The fire appeared to start in the vicinity of the CFL attic light. No other electrical (AC or battery) equipment, combustible material or wiring was in the same area except for the attic light switch and the power cable to the switch. The attic light switch was mounted on a 4 square box below the light. The light was mounted via a porcelain socket on a standard hex ceiling box. The ceiling box was mounted, so the the CFL was horizontal, on a vertical frame member about 20" below the roof.
The investigation revealed that all the wiring was proper. It was presumed that the switch was in the off position and the the CFL had not been inadvertently left on. For some reason, the switch apparently failed and provided power to the CFL. There was no evidence of fire in the 4 square switch box, but there was evidence of overheating on the conductors where they connected to the switch. The switch itself was consumed. There was no evidence of fire in the hex ceiling box and the CFL and socket were also destroyed in the fire. It was concluded that the CFL caused the fire since there was nothing else in the vicinity that could.
What is there inside a light switch that could fail in such a way to send power to the light?
What is there inside a light switch that could fail in such a way to send power to the light?
Well, a snap switch could fail to open when been turned off one last time.What is there inside a light switch that could fail in such a way to send power to the light?
Is it possible that the last time the switch was turned off it retained something resistive across the contacts which became a glowing series fault and started the fire? I know that's a reach...Well, a snap switch could fail to open when been turned off one last time.
A failure that causes continuity when actually starting from the open position is harder to imagine.
My first hunch would be the switch was inadvertently left "on" and that a loose connection on the switch or within the switch was victim to the high inrush currents of the cfl ballast. Untill it's heat gain was large enough to ignite nearby combustibles.
FWIW, I had a CFL in a lamp that started flickering and making a zzzzzttt noise. I turned it off and reached in to unscrew it, and I burned my hand on the base. That incident and this story is causing me to have concerns about the CFLs I have in recessed cans in the ceiling. CFLs in general have not (for me, anyway) lasted anywhere near as long as they are touted to.I agree with the switch being left on, but CFL inrush would be a fairly low current for a fairly short duration.
I don't quite understand how the switch, CFL lamp, and socket can be "consumed" or "destroyed", with no evidence of fire inside the boxes.
My best guess would be the CFL ballast shorted. I would assume the CFL would have some type of internal overcurrent protection, but that may have failed in a shorted mode - possibly from the heat of being left on in a hot attic. Then, apparently the current was high enough to start a fire by heating at the points of highest resistance - the switch contacts, and either the lamp ballast itself, or maybe the lamp-socket connection.
Yet, the current was low enough not to trip the branch breaker, or the branch breaker is also bad. IMO, the investigator should have tested the branch breaker also.
FWIW, I had a CFL in a lamp that started flickering and making a zzzzzttt noise. I turned it off and reached in to unscrew it, and I burned my hand on the base. That incident and this story is causing me to have concerns about the CFLs I have in recessed cans in the ceiling. CFLs in general have not (for me, anyway) lasted anywhere near as long as they are touted to.
Double thumbs up on that!:thumbsup::thumbsup: You may note that the lifetimes touted for CFL's have dropped from 23,000 hours to 4,000 hours. I eagerly wait to see what the real-life results will be for LED's.
Double thumbs up on that!:thumbsup::thumbsup: You may note that the lifetimes touted for CFL's have dropped from 23,000 hours to 4,000 hours. I eagerly wait to see what the real-life results will be for LED's.
Where do you see this reduction in claimed Life?