Dryer fire

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PaTerminator

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Location
Lehigh Valley PA
Occupation
Electrical Contractor
A friend?s house caught on fire at 3 am in the morning...
Electric clothes dryer was the cause... MASSIVE OVERHEATING!!!
Was not running at the time, no lint build-up was found...
I am looking at schematics trying to determine how this could have possibly happened and it appears that at least 3 thermostats or fuses wired in series failed for this to occur, as well as a timer switch turning on randomly.
Any input on this? Either by past experience or by knowledge?
 
C

Cow

Senior Member
Location
Eastern Oregon
Occupation
Electrician
The first thing I'd do is call the manufacturer and ask if there were any known defects or recalls issued on the dryer. I wouldn't touch the thing until I heard from them.
 
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hillbilly1

Senior Member
Location
North Georgia mountains
Occupation
Owner/electrical contractor
If I remember correctly the heating element is controlled by breaking only one leg, if the element failed to ground, that portion would heat without the dryer running. I think the safety's are also in one leg only. I have seen quite a few where the element wire melted and deflected to ground.
 
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PaTerminator

Member
Location
Lehigh Valley PA
Occupation
Electrical Contractor
I'm going to get more specic info... (model and serial #) but from I'm gathering; grounding would have to happened in series (reducing voltage to 120 volts instead of 240 across the heating element) and somehow the start switch would have to have been closed. Even at half voltage temps should have opened the operating and high limit thermostats as well as thermol cutoff fuse.
 
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gndrod

Senior Member
Location
Ca and Wa
PaTerminator said:
A friend?s house caught on fire at 3 am in the morning...
Electric clothes dryer was the cause... MASSIVE OVERHEATING!!!
Was not running at the time, no lint build-up was found...
I am looking at schematics trying to determine how this could have possibly happened and it appears that at least 3 thermostats or fuses wired in series failed for this to occur, as well as a timer switch turning on randomly.
Any input on this? Either by past experience or by knowledge?
Click to expand...

Dryer Brand and Model?
 
H

hillbilly1

Senior Member
Location
North Georgia mountains
Occupation
Owner/electrical contractor
PaTerminator said:
I'm going to get more specic info... (model and serial #) but from I'm gathering; grounding would have to happened in series (reducing voltage to 120 volts instead of 240 across the heating element) and somehow the start switch would have to have been closed. Even at half voltage temps should have opened the operating and high limit thermostats as well as thermol cutoff fuse.
Click to expand...

If the controls are in only one leg (including the start switch) then a fault to ground that is before the controlled leg would cause the element to heat. Water heaters work on the same principle, but the safety stat is double pole to prevent such an occurrence. The dryer may be set up the same way, but without looking at the wiring diagram, it's only an assumption.
 
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hillbilly1

Senior Member
Location
North Georgia mountains
Occupation
Owner/electrical contractor
Looked up a couple of diagrams on line, on the ones I looked at, the limits and temp controls were all on one leg, including the timer control. The only thing on the other leg was a centrifugal switch controlled by the motor to prevent the heater from operating without the motor running. Possibly the element shorted when it went to ground (aledgedly) welding the contact on that switch. Just a possibility.
 
Sierrasparky

Sierrasparky

Senior Member
Location
USA
Occupation
Electrician ,contractor
pretty unsafe if you ask me. This gets me thinking of electric wall heaters. If you only have a thermal on one leg and the element breaks and goes to ground then you have a potential fire. I guess I will no longer replace parts only replace whole units if the heaters are of substantial age and two pole. I bet that is why cadet has placed 2 thermals on their cheap compac plus unit.
 
T

T.M.Haja Sahib

Guest
A GFCI protection to the subject dryer might have avoided the accident.
 
Ponchik

Ponchik

Senior Member
Location
CA
Occupation
Electronologist
did the fire start in the dryer or because of the dryer but the fire started outside of the dryer?

Mr. Sahib

i dont think GFCI would have saved anything. we dont know if it was a 3 or a 4 wire circuit, and besides we still dont know what the actual cause of the fire is.
 
T

T.M.Haja Sahib

Guest
edward said:
Mr. Sahib
i dont think GFCI would have saved anything.
Click to expand...

You may be right.I still have not formed a clear mental picture of the accident.But read this post

hillbilly1 said:
If I remember correctly the heating element is controlled by breaking only one leg, if the element failed to ground, that portion would heat without the dryer running. I think the safety's are also in one leg only. I have seen quite a few where the element wire melted and deflected to ground.
Click to expand...

Based on that,I made my suggestion.You may state your counter-points that how GFCI could not have helped.
 
K8MHZ

K8MHZ

Senior Member
Location
Michigan. It's a beautiful peninsula, I've looked
Occupation
Electrician
Was not running at the time,
Click to expand...

That's the scary part.

Were there clothes in the dryer? Perhaps something failed before the end of a cycle and the dryer was actually on, just not tumbling, when the fire started.

If the dryer was empty, that may indicate the cycle was complete and power had actually been switched off before the fire, which is just plain strange.
 
K8MHZ

K8MHZ

Senior Member
Location
Michigan. It's a beautiful peninsula, I've looked
Occupation
Electrician
I am looking at schematics trying to determine how this could have possibly happened and it appears that at least 3 thermostats or fuses wired in series failed for this to occur, as well as a timer switch turning on randomly.
Any input on this? Either by past experience or by knowledge?
Click to expand...

Are you sure that it was the element that was responsible for the heating and not something else, like a cord, conductor or printed circuit board?
 
Ponchik

Ponchik

Senior Member
Location
CA
Occupation
Electronologist
T.M.Haja Sahib said:
You may be right.I still have not formed a clear mental picture of the accident.But read this post
Based on that,I made my suggestion.You may state your counter-points that how GFCI could not have helped.
Click to expand...


If it was a 3 wire circuit the GFCI probably wouldn't have worked to begin with. If it was a 4 wire circuit and the neutral and the EGC were separated in the dryer then a GFCI may have saved.

FWIW: I found this:
http://www.electrical-forensics.com/Dryer/ElectricClothesDryers.html
 
Sierrasparky

Sierrasparky

Senior Member
Location
USA
Occupation
Electrician ,contractor
edward said:
If it was a 3 wire circuit the GFCI probably wouldn't have worked to begin with. If it was a 4 wire circuit and the neutral and the EGC were separated in the dryer then a GFCI may have saved.

FWIW: I found this:
http://www.electrical-forensics.com/Dryer/ElectricClothesDryers.html
Click to expand...

I was just going to point the 3 wire item out- Darn..

At any point sitting in our chairs we can only speculate, however I can certainly see the element breaking and falling onto the metal grouded housing and just heating and heating. These types of devices need thermals on both conductors doing this will eliminate that scenario.
 
H

hillbilly1

Senior Member
Location
North Georgia mountains
Occupation
Owner/electrical contractor
K8MHZ said:
That's the scary part.

Were there clothes in the dryer? Perhaps something failed before the end of a cycle and the dryer was actually on, just not tumbling, when the fire started.

If the dryer was empty, that may indicate the cycle was complete and power had actually been switched off before the fire, which is just plain strange.
Click to expand...

I thought about that too, such as the belt breaking, which would leave the motor running and that interlock closed, possibly overheating the element causing it to fault to ground, but figured it would be too much of a stretch for that "perfect storm" to happen.
 
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PaTerminator

Member
Location
Lehigh Valley PA
Occupation
Electrical Contractor
update...

update...

OK. OP here...
I was unable to obtain detailed info for the dryer.
It was a Maytag model and had a 3 wire circuit powering it as well as a 3 wire cord.
It was not running but had some items in the drum when thge dryer caught on fire.
They were slightly burnt and damaged from the heat, but do not appear to be the source of the ignition.
 
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