How did this clothes dryer circuit start a fire?

[kwired]

But even that catastrophic failure did not ignite the house.

No. I still would put more suspect on a weak connection in the panel, and may or may not even be part of the dyer circuit.

OP possibly recreating things that had no relevance to the incident, and apparently based on code issues observed with the dyer circuit, though he was told fire started at the panel.

Don't mean to be harsh and am sorry for his loss, but just think he is looking at wrong place for answers as to why the fire started. Fire starts because of heating where it shouldn't be, not because of a green insulated conductor being used for something other than code says it can be used for, or other similar things that involve theory more so than code.

 

[tortuga]

But even that catastrophic failure did not ignite the house.

No but it was memorable enough that I always stand to the side of a panel when removing the cover.
And If i was investigating a panel fire one of the first tings I would want to know is the transformer AIC at the panel.

 

[tthh]

I think in the dryer the heater was 240 V and the motor was 120 V. So the heater was getting to 40 V and the motor was looking for the completion of the 120 V circuit. Possibly got that through the vent

Though in that scenario, I think the circuit breaker trips.

In this scenario, I don't see the circuit breaker tripping and the path through the vent is unprotected.

 

[David Fischer]

TAH
I am sorry for your loss. I also lost my teenage son in an auto accident. I also desperately looked for answers, so I understand your desire to find the cause. It has been 27 years ago and there is still a big hole in my heart.

You said that the fire appeared to start at or near the panel. You also said that this work was done by and inexperienced person. Maybe you should be looking at the workmanship of the whole job and not just the terminations. The area near the panel is very congested with the wires feeding the whole house. Could it be that there was co-lateral damage to any of those cables inside the wall near the panel while installing this new circuit for the dryer. Maybe something as simple as nicking an existing cable with the drill bit while drilling the hole for the new wire. Than 3 or 4 days later the damaged wire just happened to have enough load on it to heat up or arc and start the fire inside the wall very near the panel?

My thoughts and prayers are with you.
David

 

[kwired]

TAH
I am sorry for your loss. I also lost my teenage son in an auto accident. I also desperately looked for answers, so I understand your desire to find the cause. It has been 27 years ago and there is still a big hole in my heart.

You said that the fire appeared to start at or near the panel. You also said that this work was done by and inexperienced person. Maybe you should be looking at the workmanship of the whole job and not just the terminations. The area near the panel is very congested with the wires feeding the whole house. Could it be that there was co-lateral damage to any of those cables inside the wall near the panel while installing this new circuit for the dryer. Maybe something as simple as nicking an existing cable with the drill bit while drilling the hole for the new wire. Than 3 or 4 days later the damaged wire just happened to have enough load on it to heat up or arc and start the fire inside the wall very near the panel?

My thoughts and prayers are with you.
David

And finding and interpreting evidence that has possibly been further damaged by the fire can be tricky, especially if you haven't much experience with doing such things. General fire investigators only suggest that the fire likely started in a certain location, but seldom will state exact reasoning of why it started in such a situation. They usually don't have the electrical knowledge needed to do so, and you need to have strong physics or even chemistry knowledge and not just know a lot about installing electrical items.

 

[Hv&Lv]

And finding and interpreting evidence that has possibly been further damaged by the fire can be tricky, especially if you haven't much experience with doing such things. General fire investigators only suggest that the fire likely started in a certain location, but seldom will state exact reasoning of why it started in such a situation. They usually don't have the electrical knowledge needed to do so, and you need to have strong physics or even chemistry knowledge and not just know a lot about installing electrical items.

Agreed.
My nephews house burnt down a couple of years ago.. it was a new (<2 yrs old) house with a wood porch on the front . Like all these vinyl sided houses, there was a protected outlet on the front of the house that was easily accessed on the porch.
His wife smoked, but never in the house. On the porch. She had a coffee can she put her ciggys in when she was done. This was right beside the outlet.
Our belief is a ciggy between the siding and deck boards started the fire.
Fire chief of the volunteer fire dept blamed it on the outlet. The deck, and the coffee can were gone naturally, but burn patterns led to that area. No one mentioned she smoked...

 

[kwired]

Agreed.
My nephews house burnt down a couple of years ago.. it was a new (<2 yrs old) house with a wood porch on the front . Like all these vinyl sided houses, there was a protected outlet on the front of the house that was easily accessed on the porch.
His wife smoked, but never in the house. On the porch. She had a coffee can she put her ciggys in when she was done. This was right beside the outlet.
Our belief is a ciggy between the siding and deck boards started the fire.
Fire chief of the volunteer fire dept blamed it on the outlet. The deck, and the coffee can were gone naturally, but burn patterns led to that area. No one mentioned she smoked...

I had a friend with a house fire- smoke damage throughout of course but the burn/water damage all in the fireplace area. This guy primarily heated his house with that fireplace (wood burning old masonry type built in 1970's). Of course rumors were it must been caused by the fireplace, but the firebox and masonry were still in sound condition. I wasn't allowed in until after State Fire marshal did his investigation. He only told them the fire started at a location off to the one side of the fireplace, and that is where most the wood framing was gone or nearly gone compared to other areas - makes sense it likely did start there. He never gave any specific cause otherwise. There was copper wires, NM with all covering burned off but that to be expected whether they contributed to starting the fire or not, metallic remains of receptacles, switches, etc. in the area, some disturbed by firefighters so you don't necessarily know where they originally were located.

I asked my friend for details of where there originally was switches, receptacles, etc. and what was plugged in or in use at the time. There was a receptacle about the location where fire supposedly started. From the remains we found what was likely the metal contacts of that receptacle but have no idea if it was installed in a proper device box - if plastic it possibly could been consumed in the fire though. He said there was nothing plugged into it. The blower on the fireplace would have been only thing in the area that was in use. There was enough disturbed by firefighters that it was difficult to determine where it connected to, but a good possibility was it fed through the receptacle where the fire likely started. My conclusion though I wouldn't say was definitely the cause was there was likely "backstabbed" connections on this receptacle that supplied this blower and that they likely experienced "glowing connection" situation and it must have somehow ignited something to get this fire going. When we replaced other receptacles in the cleanup and restoration many them were "backstab" connected, and the house was around 30-35 years old at the time. Perfect age for such things to fail like that. Fireplace blower probably was somewhat low level load, but it don't take a big load to develop such heating at a connection, especially on something that runs continuously or almost continuously.