Smelt electrical burning today and found one of the wall outlets was warm to the touch (with nothing plugged in to it). I put my tester into the two outlet sockets. One read ok but the other was dead.
Took the outlet apart and found the wirenut on the neutral wires was melted!


I cleaned up the wires, including the lives, and put new wirenuts and outlet on.

This fixed the outlet on both sockets BUT other wiring in the house is not working. Some lights in an adjacent room for example.

All breakers have been reset and are firmly ON. I am not sure why the neutral would have so much current it would burn up, and how to find the root cause.

The house is old 1966 and has aluminum wiring.

Last month I had a different fault with a hot molten socket on a garage outlet. I found that one had two breakers feeding the same outlet. I isolated them, replaced the socket and that fixed it. But I wonder if it could somehow be related or give a clue?

 

Having a splice with two or three aluminum wires is a pain.
Having a splice with two aluminum wires and one copper wire is worse.

At one time it was customary to splice the two aluminum wires together and add a copper wire for the tail to the device. NoOx was a paste used on the splice to deter corrosion. Didn't help much. Even the special grease filled wire nuts were only marginally better.

Aluminiconns
Copalums - contractor crimped fittings

 

When you broke out the tab you lost the ability for the device to act as a splice to feed power downstream.

 

I recall back in the late 1970s and early 1980s there were a few brands of twist-on connectors, wire nuts, that were approved for aluminum to copper connections, using oxide inhibiting grease, and it wasn't considered a big deal to pigtail copper to aluminum for connection to a receptacle. Of course, today we know those fixes didn't last very long.

 

It may not be a lot of current flowing through the neutral, it melted because there was a poor connection at that splice. It is likely due to the aluminum wiring. I suspect you will need to keep opening boxes to find the other bad connection(s).

Standard wire nuts are not rated for aluminum splices. As far as I know, Alumiconns are the only splice rated for aluminum to aluminum wire connections.

It was fairly common for outlets to be fed by two circuits. This is fine as long as the two outlets are separated by breaking the tab between the screws on the device.

 

Last month I had a different fault with a hot molten socket on a garage outlet. I found that one had two breakers feeding the same outlet. I isolated them, replaced the socket and that fixed it. But I wonder if it could somehow be related or give a clue?

Was this a multi wire branch circuit where two hots share a common neutral? What do you mean specifically when you say you "isolated them"?

Even though nothing was plugged into the hot outlet it may be carrying significant current for downstream outlets. All the current being used by the downstream outlets is flowing through the connections in all the upstream boxes like this one. And, if you somehow left a wire unhooked in this box it can cause all the outlets downstream from it to loose power.

 

Thanks for the replies.
To clarify... The socket behind the garage fridge that burnt out had two black live wires into the socket BUT the tabs were not broken out. So both lives were connected together. When I fitted a new socket I broke the tabs to isolate them from each other and I verified with the meter they were from two breakers.

That socket is dead again and it's nearest the breakers so I'm looking at that again.
Now I've read all about crappy aluminum wiring I am going to go round the house with alumiconn's once I've found this fault.