Melting wire nuts

[Fred B]

Had an oddity once, and still not sure of how this did what it did. Had similar situation to OP on an old wiring system but it had nothing having been touched other than HO trying to replace a non working receptacle that didn't go as planned, (should have been simple enough, only one set of wires into box). Tester showed a reversal of L/N and voltage just as OP showed being on the neutral.
What eventually found was a plug-in surge powerstrip adapter that seemed to have faulted some how, that when a load applied through the powerstrip the L/N reversal reappeared and upstream receptacles were disabled. Removed the powerstrip and directly plug load into the receptacle and there was no issues of reversal. The powerstrip only created this fault when under load, simply plug in the strip and it would be fine, then apply a load and it would fault out and deaden the upstream receptacles and reverse L/N. Used a new powerstrip and everything worked fine. Still don't know the causation of the internal components failure to make the upstream issues to appear.

Guess i should have kept the strip and tear it apart.

 

[bobb123]

Seen many times neutrals of different circuits getting mixed in Jbox connections, and if the hots got mixed also and they happen to be on the same pole you can double the available amperage just like a mixed up MWBC.
The most likely heating issue leading to meltdown was a bad connection only apparent under load (vacuum cleaner).
To add to OP issue it was stated he had wires that didn't seem to have any power on them at the time he tested, these may have added another risk issue, why were these wires dead? Were they decommissioned due to a short of some sort, that might have led to an issue if reconnected into the live system? Or part of a 3way switch system?
OP reports thinking there was a L/N reversal, and simply reversed the connections in a jbox. How did OP make this determination, use a plug in circuit tester showing L/N reversed or simply a volt meter to ground?

Yes, the wires were decommissioned by just laying them in the ceiling downstairs. Some were still hot and others were not. They were all put in j-boxes where they are accessible so I can go back and see where they go and disconnect them. As I said in an earlier post, I used a voltage indicator to see which side of the receptacle showed power. I know this is crude due to the large range of voltage the indicator will pick up. Since this is a two-wire system, I did not have the option of checking voltage to ground at that point. To your point I can run a wire from the panel to various circuits to test it that way.

 

[ActionDave]

That is the oddity of it. When I use my receptacle tester to check, all it shows is an open ground, it's a two-wire system, so I am going to buy a new tester to double check that. I used a voltage indicator to see what side of the receptacle has voltage and which does not. It is showing different sides having voltage throughout the circuit. I know that's a crude way to do it, but I'm concerned for the safety so I am trying to do all I can to find the issue for them.

If you are trying to troubleshoot this with only a light up volt pen and a plug in receptacle tester then it's time to upgrade to a meter. After that you can plug an extension cord into a verified properly wired receptacle and test to see what each wire really is, be it dead, grounded, hot phase a or b.

 

[bobb123]

If you are trying to troubleshoot this with only a light up volt pen and a plug in receptacle tester then it's time to upgrade to a meter. After that you can plug an extension cord into a verified properly wired receptacle and test to see what each wire really is, be it dead, grounded, hot phase a or b.

Yes, I am doing that as well. Thanks.

 

[ramsy]

It is showing different sides having voltage throughout the circuit

Typical open neutral.
Technicians that can troubleshoot open neutrals know what to look for.

OSHA won't approve voltage sensor type Tic tracers, for false negative neutral voltage.
Since neural does not normally register on Tic tracers, any change indicating open neutral should be confirmed with Wiggy.

My Greenlee model tic tracer can also ID which side of a duplex or lamp cord has high-impedance voltage, but not low-impedance voltage.

 

[David Castor]

There may be multiple problems with the installation, but I find it hard to believe that some type of overvoltage or overload would cause a PROPERLY INSTALLED wire nut to melt. They are pretty rugged. A loose connection in the wire nut could have caused overheating and melting.

 

[ramsy]

There may be multiple problems with the installation, but I find it hard to believe that some type of overvoltage or overload would cause a PROPERLY INSTALLED wire nut to melt. They are pretty rugged. A loose connection in the wire nut could have caused overheating and melting.

Maybe for hard & heavy plastic Buchanan type wirenuts, which nobody uses.

When soft/thin-shell wirenuts are found burned up, usually in close proximity to metallic box raceways, improper installation is difficult to determine with everything destroyed including the wire.

In 2015 our forum member Al Hildenbrand responded to a similar question by posting a link for purple wirenut failures.

 

[ggunn]

Careful on that project, make sure to make detailed notes on what you have done, what you have come across and what your suggestions are to resolve the concerns directly on any invoicing. If not you could be responsible for work you had not directly installed or maybe relied upon without knowing of the existing wirings safeguards or practices, if a court order were to be filed with a liability claim or worse, you now are a person of concern.

Second that. If you change someone else's work without checking out every aspect of it, by "fixing" it you could actually make matters worse.

 

[jmellc]

Sounds like a rat's nest of the highest degree. If hidden boxes have been found, there could still be more. Neutrals could be crossed more than once in different boxes. Any number of guys could have come and gone, tapping loads from nearest box each time, hitting whichever hot and neutral had the fewest wires in the joint or that were long enough to pull out and access. Some boxes may have both lighting and power conductors, may have 3 way travelers tapped for power. I've seen that when customer had receptacles that only worked when 3 ways were in a certain position.
Best to run a new circuit to the receptacle IMHO and safe off the existing circuit. Tell customer the wiring has too many booby traps to track out and fix. You said he wants to rewire when he can afford it. Maybe work with him on rewiring a room at a time or a circuit at a time? He needs to get rid of the garbage. Other problems will no doubt arise.