This is more of a read than a plea for knowledge. It's from where we're renting and anxiously anticipating our new build completion.

I found this problem with the sensors in my nose. Actually faintly noticed it a few times before thinking to investigate. I opened all the breakers & asked the wife to call the landlord to ask for permission using an outlet & extension cord off his house next door for our fridge. She told her version of what happened which got the moo bahn involved (they're building new homes here so construction personal are on hand). They told my wife to "turn everything back on & mai bpen rai, it's perfectly normal". I had to prove to my wife it wasn't normal & very dangerous.

I could turn on any given breaker with as little as a fan or light pulling from it. That 1 neutral wire @ the bar would get up to 285 degrees Fahrenheit (clocked with IR gun) within 3 minutes (glowing).  Now I have a believer. Note: voltage was always, & still is around 232. When I first noticed this it was 300 F. The cement wall where the conduit traveled up to the attic was very warm.

Not wanting to get into this I tried something simple, cutting that chard N wire (screw was welded from heat) from the bar & the one next to it, removed the burnt sections & reconnected them @ the right side of the bar. Phenomenally, everything ran at room temperature after this simple action.

Only a few breakers pick up N & G from the box, no MEN connection & I don't want to know what goes on in the attic. I have enough on my plate to get into this so for now only some precautionary measures. Fire extinguisher, smoke alarm, landlord's aware, insurance policy's up to date & high gear on our new build. I know bad wiring is nothing unique here but just thought I'd share.

The issue was almost certainly a loose neutral connection fizzing nicely. Which is of course why everything is normal now.

 

As to how hot PVC needs to get before it ignites, 455^oC according to http://www.pvc.org/en/p/pvcs-physical-properties

 

 

Thanks Crossy. That never occurred to me since the few connections that are in there were tight, or welded. May have been cooking for some time. One less thing to worry about.