Electrical problem might have ended badly

[PineRidge]

The neighbor down the road called me this past Tuesday and asked if I might help him with an electrical problem that he was having.

Seems over the summer months he had used an older dehumidifier in the basement to keep things dry. The latter part of the summer the dehumidifier quit working as did half of the receptacles in the basement area.

Since I'm aware that most receptacles are connected daisy chain style the last receptacle in the basement that was still working would most likely be the place to start troubleshooting.

I removed the Bakelite cover plate after killing the power to find a melted area on a foam draft gasket about the size of a quarter. The wood paneling was also charred in an area about the size of a dime and the wires suppling power to the next receptacle were burnt completely off the receptacle. The receptacle itself fell apart in my hands as I was removing it from the single gang box.

Most likely this damage was a result of a loose connection and aggravated by the amp draw of the old dehumidifier. My recommendation was that the dehumidifier no longer be used, that he count his blessings, and that he say a prayer that evening thanking the man above that the home and possibly his life were spared from a fire.

I thought this might be a good story to share since it ended well. Most of the time we only hear about the unfortunate accidents that happen from day to day.

 

[riptides]

Did he move from plug to plug? Or did the line just short out all at once?

-Mike Z.

 

[schmism]

my neighbor wired up some extra recepticals. Pulled them off an existing junction box in the celing. Finnally got some real load on them (new compter and a space heater) and then all of a sudden POP! and that burnt electrical smell..... hmmmmm

im called in to help trouble shoot.

what i find? the connection in the junction box was bad. bad nutral twisting job inside the wire nut. my only guess is that over time the current draw = thermal expansion/contraction of the wires worked loose shorting to a hot.

compleately melted the the wire nut and about an inch of wire insulation. did NOT trip a breaker.

 

[PineRidge]

Mike once the damage occurred it killed a total of 4 receptacles in the basement. He had the dehumidifier plugged into the receptacle at the very end of the circuit. When it died he had enough sense not to plug it into another outlet.

 

[riptides]

L U C K Y.

Darn lucky. He should go buy a lottery ticket.

-Mike Z.

 

[PineRidge]

Hope some of that luck transfers to me, as I picked up a lotto ticket for myself.

 

[SnowRidge]

Loose connection = not gas tight and corrosion forms at the contact point.

Corrosion = resistance.

Resistance and current flow = heat.

Heat = accelerated rate of corrosion.

More corrosion = more resistance = even more heat.

We now have a positive feedback loop which soon accelerates to the point of combustion, and the circuit burns open. In most cases, the cycle ends with nothing more than a few burned up electrical bits. Unfortunately, sometimes there is a serious fire with all its consequences. Which you get is the luck of the draw.

In my experience this tends to happen most often on fully loaded circuits in damp evironments.

 

[MossRoad]

I had a similar experience with an outlet on our porch a few years ago. We kept smelling what seemed like a whiff of a dead mouse for a few weeks out there. There is just a dirt crawl space under it, so I figured that's all it was. After a while, I got sick of it and started sniffing around the walls and floor. I got to an outlet that stunk like that burnt bakelite. Funny, a few feet away smelled like dead mouse but right up to it was that disticnt smell of trouble. I pulled the cover and found the receptacle all but gone with only a few pieces of metal in there. Fortunately, the receptacle was inside a metal box. It looked like it contained the fire that was in there.

When something like that happens you do tend to count your blessings and give thanks that it was no worse. It also makes you double check your work in the future.

 

[riptides]

... Fortunately, the receptacle was inside a metal box. It looked like it contained the fire that was in there....

Sorry to go off topic for a second, I am planning on re-wiring my 100+ year old dairy barn next year. Actually in a few months... I plan on using metal casings for the wires and metal boxes for the receptacles and switches.

Why don't houses use metal?

-Mike Z.

 

[SnowRidge]

Plastic is cheaper and it doesn't conduct electricity? You can use metal in a house if you want to.