Burning Burning Burning

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aelectricalman

aelectricalman

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KY
I went into one of my Contractors homes he purchased as rental home last week. He bought the home as a repossession from the courthouse. Today I get a call and proceed to the home to look at a Clothes Washer plug that was not working. When I looked at the plug, it was fried and melted, with the wire very badly burnt and the side of the receptacle including the (Hot) receptacle opening, disconfigured badly. The wire within an inch of the plug until it met with the screw was black, melted and had green corrosion on it. I entered the panel once I put a new plug on, and noticed that all of the neutrals were severely burnt but not as bad as the plug. On the plug end, it was the (hot) side that was burnt. All of the neutrals in the panel were blackened bad and the skin of the wire was brittle. The same green corrosion was on the wires in the panel. The grounds in the panel seemed to be fine. There was no indication of burning on the grounds at the buss. The neutral and grounds are bonded via bounding screw to frame of panel. I performed a litmus test and smell acidity test to verify it was not lighting damage. What else could be a possible culprit. By the looks of the washer plug, I would guess someone tried to burn the house down. I was only half serious when the words first spewed from my mouth, but then I started thinking about the fact that the house was repo'd and that must have been alot of stress on the homeowner. Easy Insurance claim. Possibly. Could there be a way to verify just what happened so I can get this notion out of my head. It was not a bad breaker. What other things have you seen happen that could cause this? Is there a way a homeowner could do something like this given there are circuit breakers? What are some likely culprits that could cause a plug to just have a meltdown and cause trauma in the panel if everything is and was wired correctly? This to me was more than just a plug melting. This was continuous burning for some time, or a very large dose of something. The reason I say this, is if the plug were bad, the plug would have melted until the 2 sides met. At this point the brekaer would have tripped. Something stopped the breaker from tripping. Is there anything user wise that could play a role in this major burning? Thanks for the help.

[ May 17, 2005, 11:52 PM: Message edited by: aelectricalman ]
 
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I would guess someone tried to burn the house down. I was only half serious when the words first spewed from my mouth, but then I started thinking about the fact that the house was repo'd and that must have been alot of stress on the homeowner. Easy Insurance claim. Possibly.
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I would say that because the copper (an assumption) had turned green that it has been at least some time that this has been going on. Oxidation is the same thing as burning and hot wires will oxidize much faster than cold ones. But freshly heated copper wires have an orange color. They get green later. I'm not sure if you could generalize this into anything beyond a month. But I think I might guess that this condition is at least a month old.

And brittle insulation also implies that this is nothing that "suddenly" happened.

Hardly scientific, but I'd lay odds.
 
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Was this an underground or over head service,reason i am asking is here about 2 years ago there was an area where there was pretty much the same panel condition due to methane gas from the ground entering the panels.The washer recep might have had loose connections and that is the reason it melted down.
OK I say it is the doctor in the den with a knife :D
 
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I would have a very hard time thinking someone tried to burn a house down by overloading circuit's (at least on purpose). Heck I see this all the time and it is usually because of over loaded circuits or shared neutral circuits on the same leg in the panel. The green on the laundry receptacle is nothing more that the moisture produce by the dryer or washer. With the soap content of the water it is very corrosive. One reason I don't like mounting panels in a small laundry room without venting. And if the home owner uses one of those vents that "putts heat back into the house" from the dryer it will be even worse! Besides there are many way that would be much quicker and easier. :roll:

[ May 18, 2005, 03:05 AM: Message edited by: hurk27 ]
 
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Copper oxide can also be black, brown, or red depending on the thickness.

If there is a lot of moisture in the basement ( which could be a foundation defect ) copper will oxidize very fast. A leaking underground pipe for one of the downspouts or an overflowing gutter can also overwhelm the foundation drainage.

Back in the 1980s I used to do some gypsy plumbing work - putting in new underground lines for the downspouts and fixing leaking gutters would fix at least 90% of wet basements.
 
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Here are my first thoughts:

The washer plug damage sounds like typical residential-grade receptacle wear. The metal contacts inside the receptacle can lose their contact pressure over time with large loads.

I've seen it most often with clothes dryer receptacles. For some reason, it seems to happen to the line that feeds only the heater, so people sometimes buy a new dryer unnecessarily.


If every neutral has been heated at the bus, and the hots didn't have any damage, it's possible the the bus was the cause. What could cause the neutral bus to be overheated? Loads? Maybe not.


(Partly off-topic rambling):
Last year, I responded to a call about an electrical fire. The 10/2 NM cable feeding the water heater had burned, but didn't trip the breaker. It took me a couple of hours to deduce the cause.

I couldn't figure out how the 10 gauge cable overheated without tripping the breaker. Bad breaker? Maybe, but both poles? The main hadn't tripped either. What could have happened?

It was a 200-amp QO panel, back-to-back with the meter. Once I opened the panel, made some mental notes, and sat on it for a few minutes, it dawned on me; the neutral had become energized!

The pertinent clues: the panel had illegally been "upgraded" from 100 amps, as evidenced by the #2 aluminum SE cable above the meter, no water or driven grounds, no cable clamps anywhere.

I coulUpon closer inspection, I realized that it was the EGC in the water-heater cable that had burned. That was the only "ground" for the panel, the copper water pipes attached to the heater.

Apparently, there was either a temporary primary-to-secondary fault at the transformer, or a line-to-neutral short on the triplex. The POCO had to shut off the block to make repairs, I was told.
(End ramble)

Is it possible that the neutral bus somehow became a low resistance bewteen the service neutral and the local grounding paths? (I try to land my water and driven grounds nearest the main neutral lug.)
 
Re: Burning Burning Burning

Originally posted by aelectricalman: At this point the brekaer would have tripped. Something stopped the breaker from tripping.
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If it puts your mind more nearly at ease, let me offer the opinion that there isn't anything a user can do that would prevent a breaker from tripping. They are designed to be "trip free," so even if the resident tried to wedge the breaker handle open, the breaker still would have tripped. I'm not into forensic science, but to me this does not sound like an intentional act.

The only way to bypass the breaker trip feature would be to bypass the breaker itself, by somehow hard-wiring the load to the panel's bus work. But that would have left obvious signs within the panel.
 
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Thanks for all of the great input. The most promising lead thus far is the transformer prim's and sec's possibly temporarily shorting, or the possibly the neutral conductor was energized.. Thanks.
 
Re: Burning Burning Burning

I performed a litmus test and smell acidity test to verify it was not lighting damage.

I just couldn't let this one go. What the heck are you talking about?

-Hal
 
Re: Burning Burning Burning

I would check out the neutral bar for any cracks. I found a panel one time that the neutral bar was actually cracked where the service neutral connected.

The neutrals all showing signs of heat stress lead me to look hard at the neutral connection to the service, plus the grounding of the service neutral.

Please let us know what you find.

Also, what is that lightning test you are talking about? First time I've heard about that.
 
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Most insurance companies around here require a litmus test for lightning damage verification. You stick a peice of white litmus paper in a vial with a scraped off peice from the damaged area into the solution that comes with the kit. If the litmus turns pink, voila, theres lightning damage. Lightning damage creates a higher amount of acidity than other electrical problems. The litmus test is a test for that higher dose of acidity. Also, you can smell the acidity. Have you never smelled acidity? Also, there is an oil test for acidity. Easy verification for lightning. Has anyone else ever used this for an insurance company or yourself?
 
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