Wire nut fail

[Yellowboat]

Never seen one melt like this before.

 

[Yellowboat]

Explains why one of the outlets was putting out 220

 

[SoCalDave]

Yes, that is an unusual failure.

 

[RCDave]

Is the house wiring copper? Wonder if the breaker for that circuit is correctly rated/functioning properly. Maybe the wire nut connection was not tightened sufficiently?

Scary...

 

[Yellowboat]

It's a 20 amp breaker and number 12 wire, the only thing I can come up with is since the home owner had a rat prob recently, they must have chewed the wires making one of the netrals hot. Ofc it is in a kitchen and it' a sheer wall, with zero access from the other side.

 

[Mandelon]

Scary!

 

[Taboma]

Never seen one melt like this before. View attachment 636805

Odd indeed. I'm tempted to believe one of the neutrals was only barely captured either by the conductor being cut to short, or perhaps the insulation interfering. Doesn't surprise me considering the other nasty shit going on in that box. Exposed conductors on the red and black wires, the attempted creation of a jacket using electrical tape for the same two --- holy shit, it's a mess. Wonder what else that same hack wired up in that fire trap ?

 

[Taboma]

It's a 20 amp breaker and number 12 wire, the only thing I can come up with is since the home owner had a rat prob recently, they must have chewed the wires making one of the netrals hot. Ofc it is in a kitchen and it' a sheer wall, with zero access from the other side.

Don't think so on the rat causing a direct short --- a heating, melting like that is usually a high impedance connection that won't trip a breaker, but over time fails --- These are the most dangerous types of failures, often by burning a home. As the connection heats, it creates more resistance, creating in turn more heat. If the failure isn't immediate, the heat damages the conductors and the spring in the connector, resulting in more resistance. Next time it gets worse, so on and so forth ---- it's a cascading effect.

 

[Yellowboat]

As the home was built 2006. The above stove microwave vent box was put in the wrong spot, so my guess is the applince installer put a old work box next too it and used what ever he had. Still does not explain the white being hot, my guess is still rats chewing stuff would not be the 1st time.

 

[Yellowboat]

Don't think so on the rat causing a direct short --- a heating, melting like that is usually a high impedance connection that won't trip a breaker, but over time fails --- These are the most dangerous types of failures, often by burning a home. As the connection heats, it creates more resistance, creating in turn more heat. If the failure isn't immediate, the heat damages the conductors and the spring in the connector, resulting in more resistance. Next time it gets worse, so on and so forth ---- it's a cascading effect.

This started out as a bad gfci, when I pulled it that is when I found the double hot going too it. One of the whites in the box is still hot even after disconnecting every thing on that circuit. Getting ready to go in the attic now and trace the wires back.

 

[Yellowboat]

Great, the power going too the neutral is coming from the lighting circuit. So either there is a bad junction in one of those boxs or a bare conductor some where.

Fun stuff. I think I am about ready too call my electrical sub and have him do this. I really don't want too rewire a house.

 

[Taboma]

This started out as a bad gfci, when I pulled it that is when I found the double hot going too it. One of the whites in the box is still hot even after disconnecting every thing on that circuit. Getting ready to go in the attic now and trace the wires back.

Well damn, that is an odd one then. Because the fault that caused the white to become hot, should have tripped the breaker and the damage should have occurred and be evident there, not at the point where the wire nut melted.

 

[RCDave]

Ahhhh Eeeee Yaaaaa!

 

[Yellowboat]

Well damn, that is an odd one then. Because the fault that caused the white to become hot, should have tripped the breaker and the damage should have occurred and be evident there, not at the point where the wire nut melted.

Yeah has me scratching my head as well. That is why I am really thinking the rats chewed a wire. I can not see them running nuetral thru a curling box some where., luckil the gfci took the a shit otherwise it very easily could have been a fire.

 

[hallett21]

Wire nut like that makes me think loose neutral.

The 240 part is odd... some where you have another phase on that neutral.


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[Yellowboat]

Yeah, it is coming from the lighting circuit

 

[Taboma]

Wire nut like that makes me think loose neutral.

The 240 part is odd... some where you have another phase on that neutral.


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Making me think as you mentioned that's a shared neutral on a 3-wire home run.

 

[Waterjunky]

Not a professional a this but if the neutral in the breaker box became disconnected (required to stay hot....) then you are back feeding from anything else on that circuit and using this as your ground?

 

[Taboma]

Not a professional a this but if the neutral in the breaker box became disconnected (required to stay hot....) then you are back feeding from anything else on that circuit and using this as your ground?

If you're referring to a circuit with a single 120V hot and paired neutral, then the circuit is simply open if the neutral is disconnected at the panel (Neutral bus).
If you're referring to a circuit with two 120V hot phases (A&B Phase) sharing a single neutral (Romex with a black, red, white and ground) then very weird things start happening as various loads get turned on. Essentially if only one load sharing the entire circuit is energize, the circuit will be dead (Open), as it will if you turn on multiple, but if they're all on the same hot phase. The weirdness starts as soon as you energize a load on the 2nd phase, because now the return path travels between phases through the loads. Think of it like loads now being in series instead of parallel.
The loads are acting as resistors, the more loads turned on between both phases the less resistance, voltage increases, same as with resistors in parallel. Eventually the voltage climbs and starts blowing shit up or lamps start popping.

Hope this helps more than it confuses

 

[highvoltagehands]

An Overloaded circuit with loose neutral connection under wire nut can cause meltdown too. Twisting conductor connections together (aka "Cold Soldering") with Kleins before applying wire nuts will help avoid a lot of problems. FYI I remember my apprenticeship instructor saying All UL listed Romex wiring manufactured since 70's has Rat/Mice deterrent built into insulation to prevent gnawing.

 

[GRADS]

I'm guessing the black cloud following you probably rained on the wire nut and got it wet. Boom shorted out.

 

[Taboma]

An Overloaded circuit with loose neutral connection under wire nut can cause meltdown too. Twisting conductor connections together (aka "Cold Soldering") with Kleins before applying wire nuts will help avoid a lot of problems. FYI I remember my apprenticeship instructor saying All UL listed Romex wiring manufactured since 70's has Rat/Mice deterrent built into insulation to prevent gnawing.

Since Grad's just blew this thread sideways to satisfy his need to poke the bear, I'll also digress.

This one's right up your "High Voltage" alley.
Years ago I was running a job at a large naval installation, we were replacing all the 15KV UG and primary/secondary substations on the base. Due to it's proximity on the bay and high water table, the manholes were always filled and splices had to be really tight as they had to survive submerged.

Navy contract required a CQC quality inspector on site daily to monitor field work and log everything. Ours was a budding attorney, couldn't screw a nut and bolt together, but with instructions in hand, he'd sure try to tell you how and be ready to torque test as you went. In other words, more often than not, my crews wanted to encase him in concrete for eternity.

We'd just started the splicing and as I approached the manhole I notice my trusty CQC inspector perched by the opening and now I'm seeing rolls of tape and other splicing materials flying up out of the hole --- WTF ? Specs required taped splices and the CQC inspector demanded to watch and follow along with the instructions, at least for the first couple of splices.
So splicer is cussing up a storm, throwing anything he can grab at the inspector, CQC is backing away from the hole to avoid getting hit. Finally get this splicer, who'd been wrapping tape back when I was in grade school, to calm down and tell me what the problem was.
The problem it seems was, the splicer was left handed, the 3M splice instructions were for a righty, so the big fight was over the CQC, sitting there instructions in hand, telling the splicer he was wrapping the tape backwards The ole guy who could have done these in his sleep, with his eyes covered, was done. By then it didn't matter that I'd convinced the moron inspector the direction of the wrap didn't matter, my best splicer walked off the job.

 

[Rvrluvr]

Since Grad's just blew this thread sideways to satisfy his need to poke the bear,

I dont think so. Yellowboat has either the worst luck of anyone on eart or a big drama queen. Its always the sky is falling

 

[Taboma]

I dont think so. Yellowboat has either the worst luck of anyone on eart or a big drama queen. Its always the sky is falling

Yes, I'm aware of Yellowboat's tales of woe and disappearing Lexuit, but I took this one as sharing a customer's forensically interesting electrical failure. He didn't cause or create the problem, simply trying to diagnose it.
Hence, I stand by my opinion

 

[Groper]

Wire nut like that makes me think loose neutral.

The 240 part is odd... some where you have another phase on that neutral.


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This ^^^^ with (2) circuits or "A" phase using the same neutral double the load on the neutral=Heat and loose wn will do the same as mentioned.
If you had a two different phases it would have popped when you tried to close it.
I have seen this multiple times during a remodel or panel change outs.

 

[highvoltagehands]

Since Grad's just blew this thread sideways to satisfy his need to poke the bear, I'll also digress.

This one's right up your "High Voltage" alley.
Years ago I was running a job at a large naval installation, we were replacing all the 15KV UG and primary/secondary substations on the base. Due to it's proximity on the bay and high water table, the manholes were always filled and splices had to be really tight as they had to survive submerged.

Navy contract required a CQC quality inspector on site daily to monitor field work and log everything. Ours was a budding attorney, couldn't screw a nut and bolt together, but with instructions in hand, he'd sure try to tell you how and be ready to torque test as you went. In other words, more often than not, my crews wanted to encase him in concrete for eternity.

We'd just started the splicing and as I approached the manhole I notice my trusty CQC inspector perched by the opening and now I'm seeing rolls of tape and other splicing materials flying up out of the hole --- WTF ? Specs required taped splices and the CQC inspector demanded to watch and follow along with the instructions, at least for the first couple of splices.
So splicer is cussing up a storm, throwing anything he can grab at the inspector, CQC is backing away from the hole to avoid getting hit. Finally get this splicer, who'd been wrapping tape back when I was in grade school, to calm down and tell me what the problem was.
The problem it seems was, the splicer was left handed, the 3M splice instructions were for a righty, so the big fight was over the CQC, sitting there instructions in hand, telling the splicer he was wrapping the tape backwards The ole guy who could have done these in his sleep, with his eyes covered, was done. By then it didn't matter that I'd convinced the moron inspector the direction of the wrap didn't matter, my best splicer walked off the job.

That's Hilarious Taboma! I can totally see an inspector saying something stupid like that. He'd make that mistake once. I would've informed him that "Left to right or right to left" doesn't matter, an experienced tape splicer will always push the roll away over the top in order to stretch the tape and avoid "the void" that's important. He can caliper it afterwards and if the taper isn't correct, I'll tear it off and redo it on my dime.

 

[Taboma]

That's Hilarious Taboma! I can totally see an inspector saying something stupid like that. He'd make that mistake once. I would've informed him that "Left to right or right to left" doesn't matter, an experienced tape splicer will always push the roll away over the top in order to stretch the tape and avoid "the void" that's important. He can caliper it afterwards and if the taper isn't correct, I'll tear it off and redo it on my dime.

Thought you'd appreciate that
Trust me, before I rolled up and shit started flying outta the hole, there had already been some heated discussion about tape direction and how far the inspectors head was inserted up his ass, lol
After a similar "You've got to be shitting me" discussion with this ass-clown in my trailer one afternoon, I chased him all the way across our storage yard, into an adjacent office trailer where he took cover behind our rather robust secretary

 

[highvoltagehands]

I would’ve intorduced him to 25kv “Silent Splice” to quiet his “chin music”!
Start’s with Scotch 70 self fusing silicone tape to seal his trap,
Followed by 130C insulating tape so no one could hear him, followed by 33+ For everlasting protection against failure and bitching. Good for 25kv or CQC.

 

[rrrr]

Making me think as you mentioned that's a shared neutral on a 3-wire home run.

That's what I think.

 

[Classic Daycruiser]

I would swap out the breaker. It should have tripped.

 

[rrrr]

I would swap out the breaker. It should have tripped.

A loose connection can develop enough heat to melt a wire nut without drawing sufficient current to trip the breaker.

A 20 amp circuit can produce 2.4 kW. Half that amount of heat concentrated on a loose connection can easily melt the wire nut.

 

[Yellowboat]

It also was caught by a gfci. Which ended up roasted. My electrical sub is start a complete rewire Tuesday. He said half the circuits were messed up and it would be safer to get rid of all of it rather then just the bad parts. It's his job now and his insurance now.

 

[HST4ME]

 

[LB247XS]

That's a typical situation for a loose connection inside the wire nut and it just sits there and arcs overtime and just eventually melts the wirenut me being an electrician and doing many residential service calls ran into that hundreds and hundreds of times

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[DirtyWhiteDog]

Was it not common practice in residential prior to the '99 NEC to tie all neutrals together at any and all boxes ?

 

[Taboma]

Was it not common practice in residential prior to the '99 NEC to tie all neutrals together at any and all boxes ?

Never, only if those neutrals are paired with their specific branch circuit(s). Connecting all neutrals, including ones not associated or paired with the branch hots, creates an extension of the neutral bus, a flagrant violation.