Fred B
Senior Member
- Location
- Upstate, NY
- Occupation
- Electrician
How did this clothes dryer circuit start a fire?
- Thread starter TAH
- Start date
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kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
The dyer motor likely doesn't draw all that much current that a 14 AWG can't handle it. Maybe 5 - 6 amps max. The 240 volt heating element is the major current drawing component in a dryer. But if you somehow end up only supplying 120 volts to that element, it also only draws maybe 5-6 amps.
If there was an issue with current in the vent pipe why would the fire start in the panel and not in the vent pipe?
Sounds to me like there was an issue in the panel and may or may not even be associated with the dryer. Yes there may be code violations with connecting ungrounded supply to white or green insulated conductors, but that alone isn't starting a fire. Current and voltage don't recognize insulation color, just paths of continuity.
Sorry for your loss, I posted this before I got to the post where you mentioned this.
Still when it comes to finding out what went wrong, you seem to keep looking for things at the dryer but said the fire started at the panel - dryer might not be a direct the cause of the fire.
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synchro
Senior Member
- Location
- Chicago, IL
- Occupation
- EE
jeff48356
Senior Member
- Location
- Livonia, Michigan
My deepest condolences for the OP's loss. But who installed the panel? Was that done by a licensed electrician? Was it inspected and approved by the AHJ?
Folks, THIS is why I am against DIY'ers and handymen taking on electrical projects. They know just enough to make them dangerous. There are a few exceptions, but 9 out of 10 should not be working with electricity.
Folks, THIS is why I am against DIY'ers and handymen taking on electrical projects. They know just enough to make them dangerous. There are a few exceptions, but 9 out of 10 should not be working with electricity.
- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
I do not see any movement in this direction in this thread, but I still would like to remind all of the T&C of the Forum that any opinions or statements here are not to be cited as evidence in legal proceedings. Exploring the possibilities with OP seems perfectly appropriate.
TAH
Member
- Location
- Camden, ME
- Occupation
- electrician
Thanks to all of you. I will update you as I progress with studying this incorrectly wired dryer circuit.
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
If the fire stated in the panel then closer examination of the panel is necessary to hopefully determine what failed within the panel. Even if there was code violations in the branch circuit to the dryer that doesn't necessarily mean it is automatically what caused the fire. Your most likely sources are heat caused at a poor termination or a breaker that for some reason failed to trip under overcurrent conditions leads to excess heating in some component/conductor/etc. Miswiring of the dryer could cause that overcurrent condition but breaker should still have tripped.
That said those failed connections inside an enclosure burn themselves out most the time and leave the circuit non operational, but if there is enough ignitable material present in close proximity then you have better chance of igniting that material and have fire spreading more easily.
- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
A poor termination of a wire inside the panel can certainly result in excessive heat without a current that would even trip the thermal element of the breaker. But the local heating a the lug of a breaker could cause it to trip at a lower current than normal. The miswiring at the dryer could conceivably cause a continuous current draw close to or in excess of the thermal trip limit but not enough to trigger a magnetic trip. Even with a faulty breaker and a bad termination the usual result is simply burned wire contained inside the panel.
I suppose that if paper filler from NM is sitting inside the panel it could conceivably allow fire to spread outside the panel. Wire insulation should never by itself allow conduction of flame outside the panel, IMHO. But heating of the wire extending out of the panel might.
synchro
Senior Member
- Location
- Chicago, IL
- Occupation
- EE
From what was described, the only unusual condition on the panel side was that 10A was flowing on the EGC for the dryer circuit. Now that shouldn't cause a fire if all of the connections were good, but conceivably it might if there was a bad connection at some vulnerable location (assuming that one exists). However, before this dryer was wired up presumably there was negligible current in the EGCs, and so a bad EGC connection would have no effect (unless, of course, a significant ground fault occured). But after dryer was wired as described, 10A in the EGC might have exacerbated a lurking problem. Just speculation, but all I can do on this end.
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SG-1
Senior Member
- Location
- Ware Shoals, South Carolina
First, very sorry for your loss.
Pyrophoric carbonization at the panel was caused by the dryer vent being energized & in contact with numerous wood members of the structure. Just the one mistake, the energized white wire connected to the dryer frame could have caused this...
Pyrophoric carbonization at the panel was caused by the dryer vent being energized & in contact with numerous wood members of the structure. Just the one mistake, the energized white wire connected to the dryer frame could have caused this...
So sorry for your loss.
I've been watching this thread, I'm curious to see if your test set up reveals anything.
"The fire pattern seems to show that the fire started at the circuit breaker panel"
Had a Square D QO panel burn starting at the buss bars where a 2 pole ac breaker attached. The main did not trip. Smoke filled the basement and the home owner was home to make calls to the fighter department to cut power and stop fire which was contained to panel interior.
Not doubting, but maybe the fire was unrelated to the miss wired dryer. ???
I've been watching this thread, I'm curious to see if your test set up reveals anything.
"The fire pattern seems to show that the fire started at the circuit breaker panel"
Had a Square D QO panel burn starting at the buss bars where a 2 pole ac breaker attached. The main did not trip. Smoke filled the basement and the home owner was home to make calls to the fighter department to cut power and stop fire which was contained to panel interior.
Not doubting, but maybe the fire was unrelated to the miss wired dryer. ???
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
What was described is a mock up application tying to simulate what was installed, we don't know if he missed say making the same bad connection in the mock up that maybe was in the application that started a fire, or since he said it appeared the fire started at the panel we don't really even know if the dryer had anything to do with starting this fire. OP seems to have discovered things that are not typical of a code compliant dryer installation and is assuming that must be related to starting the fire. Conductors don't care what color the insulation is, you hook a green conductor to an ungrounded terminal - it becomes an ungrounded conductor. Land that green on "ungrounded supply terminal" of the appliance - it don't care what color it was it still sees ungrounded supply conductor. I didn't follow exactly what he had with what color was to what, but for the sake of finding out what started the fire he needs to forget that and figure out what was grounded what was ungrounded and whether or not it was the combination the appliance needs to work as designed. Losing track I once thought there might be 240 volts applied to what should be 120 - that can be a problem but probably not going to have very high risk of starting fire at the panel, unless maybe breaker simply does not trip under the high current that may be flowing for some reason, but even then about has to be ignitable material in the vicinity or as Golddigger mentioned it likely burns open a connection eventually as far as what may happen inside the panel.
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
If it is poor breaker to bus connection situation the smoke is likely from the plastic bus supports and/or plastic breaker case. They are still made of a plastic that won't ignite very easily, but get them hot enough and they still can. The connection is likely going to fail enough it becomes "open cicuit" before it will get that hot though.
The main don't trip as it doesn't get hot enough nor is it carrying "overcurrent" level of current. Seldom does the branch breaker effected seem to trip either. Think has more to do with location of thermal overload element inside the breaker. Bad connection on load side of breaker does seem to trip breakers more so than on line side on these plug on style breakers though I haven't seen load side with bad connection nearly as often as bad breaker to bus connections.
Thank you, I agree. Just interesting how it loosened after years of use with no issue. Or maybe it was always loose and just being used in summer took a decade or more to finally fail. As a side note, besides the rust on the panel bottom, look at the rust on the rivets of the breaker. Where I use to think alittle rust on those rivets was not a biggey I now have a different opinion when I see rust on breaker rivets when I see it.
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
rust on the rivets isn't too much of a direct problem, though if it is there then there is probably other possible issues. I'd guess water has been entering this panel. Even if just condensation draining down a raceway - common one is top entry of the supply conductors, condensation drips onto main lug/main breaker not only working on integrity of main but also continuing down the bus working on integrity of bus to breaker connections. Doesn't have to be a QO panel either.
SE cable with a leak in the sheath does same thing eventually but not so much from condensation only. Improper made up "drip loop" in overhead supply transition also a contributing factor and water follows the individual conductors in the gaps between strands inside conductor insulation.
SG-1
Senior Member
- Location
- Ware Shoals, South Carolina
I have seen that hole pattern in the second picture before. Several 15A breakers in my panel were showing a discoloration on the side with a similar pattern.
Drilled out the rivets & found the breaker contact there. Replaced every 15A breaker in the panel.
No loose wiring found. The contact resistance was slowing increasing through the decades of service.
I know that many, many members have posted their deepest support, & sympathy.
Although I cannot add any different views, I can add that I also... am so, so sorry!!!
And as previously mentioned, please be very careful with your test mockup.
Bill
Although I cannot add any different views, I can add that I also... am so, so sorry!!!
And as previously mentioned, please be very careful with your test mockup.
Bill
TAH I am truly sorry for the loss, I am sitting here stunned....
I can add an odd call i had many years ago;
It was a call for a 30A breaker that blew and broke in a older panel,
someone had mis wired a baseboard heater thermostat to a dead short.
The main in the panel was old and tripped so hard it broke apart when I opened the panel cover, I had to pull the meter and later replace the whole panel.
I never figured out the exact cause but I suspected the utility had replaced a transformer upping the available fault current beyond what the old breakers could handle. It was a dense neighborhood with a very large transformer near the house.
I can add an odd call i had many years ago;
It was a call for a 30A breaker that blew and broke in a older panel,
someone had mis wired a baseboard heater thermostat to a dead short.
The main in the panel was old and tripped so hard it broke apart when I opened the panel cover, I had to pull the meter and later replace the whole panel.
I never figured out the exact cause but I suspected the utility had replaced a transformer upping the available fault current beyond what the old breakers could handle. It was a dense neighborhood with a very large transformer near the house.
But even that catastrophic failure did not ignite the house.
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