Electrical fire last night

The 220 outlet box for my dryer caught fire last night, both it and the plug were damaged, but fortunately nothing else. I saw the flickering light on my security camera. At first I thought the RGB light I built a few weeks ago was malfunctioning. It's really bright, but fades slowly, and no flicker. So went out and checked. The outlet box was flaming up pretty good, really sucked because it had been raining earlier, everything around it was wet. Had to grab the dog, he's a curious puppy, and its 220 and fire. Flip the breakers, went back out, but still burning pretty good, covered it with some scrap aluminum, died out quickly.

This was really strange, as I ran this 220 about 14 years ago, and it's been through hurricanes. The rain we've been getting hasn't been anything spectacular, why flame up now? Will admit that I don't much about house wiring, but do it anyway. This was my first 220 run, which involved considerable guessing, surprised it worked. Can only guess that some water got in, maybe a bug or something.

Going to Home Depot when it opens, and get a new box, and see if they have a longer cord for the dryer. If not, I'll just replace the cord. Yeah, going to just put it back as before. If I get the longer cord, I can put it inside the house, if not, I'll have to shelter it, so it doesn't happen again. Lucky I was home, and had the security cameras, could have been much worse. The wires seem fine, weren't even warm to touch, even with the flames.

Kind of got me rethinking a project I've had in the works for a while. I was going to put some large, simulated flame, torch style lights out in my yard, solar powered. I've got some small ones that do candle flame okay, and my solar has moved up to 12 volts, but I'm thinking how lucky I was to notice the unusual flicker of light.

You have a 220V electric clothes dryer outside in the rain??

audioguru said:

You have a 220V electric clothes dryer outside in the rain??

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Yes, but it's on my back porch, under the roof. It gets a little wet sometimes, but usually not soaked. I've had it there pretty much since I bought the house.

Just got through replacing the cord. It's 6 feet, and long enough for me to mount the outlet inside. Now for the fun part...

If the wire connections loosen up they can cause increased resistance or arcing which can lead to a fire. In the article at this **broken link removed** they talk about vibration causing a loose connection to get worse and increase the temperature to about 400 C. I wonder if vibration from the dryer could have done the same.

I don't think it was vibration, maybe years of oxidation and a little rain. I do laundry once a week, usually Sundays. So, it was sitting for a week, also rained some pretty much everyday last week. The wires inside the outlet box weren't scorched, melted, or burned. I just left them as they were, when I installed the new box (drying clothes right now). Will have to take a closer look inside the box later, only removed the wires last night under the light of a flashlight. More concerned about making it safe to flip the breaker back on.

The new box is all metal, grounded, and firmly attached to a concrete block wall, inside the house. Shouldn't be a problem again.

The fire was likely caused by a high resistance contact, either between one of the wires and the socket, or between the socket and plug contacts. With, perhaps 15A going through the wires, it doesn't take much resistance to create a lot of heat.

The wires aren't aluminum are they?

Just glad your house did not burn down. Was the wiring up to code? GFCI?

crutschow said:

The fire was likely caused by a high resistance contact, either between one of the wires and the socket, or between the socket and plug contacts. With, perhaps 15A going through the wires, it doesn't take much resistance to create a lot of heat.

The wires aren't aluminum are they?

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Nope, all copper, brass connectors. Still seems pretty weird, all wires were fine, just the black plastic cover on the outlet burned, which melted the plastic on the dryer plug (didn't really burn). I re-used the 220 line from the breaker, looked clean and bright, insulation looked good. Just did two loads of laundry, so no immediate faults. The dryer cord plug was still solid, but slightly exposed. Didn't want to risk it.

Mikebits said:

Just glad your house did not burn down. Was the wiring up to code? GFCI?

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The house was built in 1946, so probably consistent with the rest of the wiring... No GFI in 1946, or now. Maybe time for an upgrade, only one more mortgage payment, then I can start getting things modernized. I think the plumbing needs more attention though. Anyway, I barely understood the 220 wiring, adding GFI? Think that's best left to a professional.

HarveyH42 said:

The house was built in 1946, so probably consistent with the rest of the wiring... No GFI in 1946, or now. Maybe time for an upgrade, only one more mortgage payment, then I can start getting things modernized. I think the plumbing needs more attention though. Anyway, I barely understood the 220 wiring, adding GFI? Think that's best left to a professional.

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A GFI only protects against ground faults, that is, current from a hot line to earth ground. It's designed to protect people from electrical shock. It's not likely that it would have protected against the type of failure you had (a high impedance connection in the line) since there was no ground current involved in the fault.

GFI's are mandatory in our area for new construction bathroom, kitchen, garage, and outdoor outlets. They simply replace the standard outlet or standard service box circuit breaker. They require no additional wiring and are not difficult to install. I think they're a worthwhile safety addition to any house that doesn't have them.

I'd rather rely on a healthy respect for deadly currents, it's kept me safe so far.

GFI should protect against basic outlet fires, assuming the GF circuit itself wasn't what was on fire =O The plasma, general heat and high currents are going to cause some kind of ground current to flow very fast. Sounds like you're the victim of bad drainage and insufficient house inspections. Rain can fall 1000 times on the same spot and drain the same way and the 1001th time fall a different way because of a single leaf dropping in a bad place. Drain into the wrong crack, crevice, or nook, next to a piece of wire which will provide a path further into the structure.. eventually you'll end up with water dripping into an electrical outlet from a path it never has before. Basic chaos theory =>
Ever seen the direction for installation of a fish tank heater or filter system? They 'strongly' recommend a dip in the system bellow the outlet in case water hits the wires at the top and drips down into the outlet. Suffice to say, if the wire enters from the bottom of the outlet you have some basic physical protection from water infiltration from physics itself, a generic electrician won't usually do something like that.
I'll hazard a guess that outlet was wired vertically.

Actually, it the box wasn't anchored to anything, just laying on top of a concrete block, next to the dryer... The dryer cord wasn't long enough to reach all the way to the wall, let alone inside the house, so I ran the 220 out to it. It's had a lot more then a few drops of water dumped on it over the years, several hurricanes have passed over us. Will post a few pictures of the inside of the outlet. Still haven't taken a close look, was just glad to get the dryer running, and my clothes done.

Pretty obvious from the second picture, a good amount of dirt an debris insid the cover. Not really bad for 14 or so years, but enough to start a fire...

HarveyH42 said:

I'd rather rely on a healthy respect for deadly currents, it's kept me safe so far.

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Certainly you should respect all high voltage circuits and not depend upon some safety device to protect you. But GFI's are good in case a power applicance develops a short to the case that you may touch, or some child goes poking a wire into a socket (Some time back I was unplugging two extension cords in my garage and accidently touched the plug blade as the plug came apart. Got a nasty jolt but it tripped the GFI. Perhaps saved me from my goof.)

I only see three connections. Hopefully one wire isn't doing double duty as Ground and Neutral!

mneary said:

I only see three connections. Hopefully one wire isn't doing double duty as Ground and Neutral!

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I'm guessing that it is. I've got two wires coming off a double breaker, the third is the ground, no neutral. Don't remember how I came to doing it this way, but it works. Always thought it was a little weird, but didn't know anything about 220 when I put it in, still don't know any better. Not really something I'm comfortable working around. Really hate getting shocked.

220VAC in North America is the hot 110V wire from one phase, the hot 110V wire from the 180 degrees phase and a protective ground. Neutral is not used.
Neutral is used for 110VAC receptacles.

Frequently a duplex receptacle in a kitchen has one receptale with 110V/15A from one phase and the second receptacle with 110VAC/15A from the 180 degrees phase. Then the neutral is shared by both receptacles.

You have this **broken link removed** and a modern dryer has this http://www.hubbellcatalog.com/wiring/images/9430a_diagram.jpg. Both supply dual voltages, 220 vac for the elements and 120 for the motor and drum light. Most alll dryers I've worked with in many decades were of 120 volt motors, some 220 volt motor model may exist, don't know.

The modern dryer incorporates a independent ground wire which carries no current unless there is a fault, whereas the older style plug assumes that the ground and neutral are connected together at the main box.

However, if one uses the older plug and if one uses a separate sub panel box, depending on the associated resistance from the length of the wire from the bond or a poor connection in the receptacle a voltage drop may develop from neutral and ground (either electrical ground or the wet dirt ground that you stand on). Coupled with a fault in the appliance and you may be in for surprises.

Your situation, considering you admit it was your first 220 wiring and that you were surprised it worked and that a outside non GFI outlet was just laying on a concrete block in the wet environment you describe, is scary.

Since you have, for some unknown reason, a 220vac appliance in a wind driven rainy area you are lucky that you are telling people about it. Yes, maybe in was fine for 14 years but one night it was not. Of coarse, you are lucky your camera picked it up and your lucky that you were home and you were lucky that you happened to be watching the monitor. Have you thought about buying a lottery ticket? I'm curious, do you bathe with a plugged in toaster or hair dryer sitting on the edge of the tub?

Sorry for the sarcasm but should get an electricians opinion.

It would be interesting to stick one probe of a meter in the ground and another to the frame of dryer to see what kind of reading you get.

Guess the reason I've never gotten even a tingle off it, is mostly I don't use it in the rain, and only a couple of loads per week. Also might have something to do with it sitting on a concrete slab, a better path.

I've no problem with sarcasm, well maybe I use it a little too much myself...

Only guessing, but to ground the frame, I'd need to drive a metal rod a few feet in to the dirt, and use it. Since the circuit breaker ground is being used as the neutral. I know, just having outside is a bad idea, but it doesn't fit in the house.