I’ve come across a few circuits in Berkeley that have been failing on the return side of 120 volt receptacles? Arcing enough to melt the face of device, in a recent kitchen remodel 2006? All inspected but failing where 1500 watt appliance have been used not old appliances? I believe all were 20amp leviton devices, all new Romex circuits? Possibly just poor workmanship? No loose connections that I’ve found?
I would lean toward the quality of the terminations (workmanship/talent)
You don't mention if the terminations are on the screw terminals, if it's #12 or #14 NM, or if the devices were 'backstabbed'
We come upon a few burnout receptacles, and IMHO, termination quality is an issue.
I am not aware of any device issues in the early 2000s.
As to your comment on the job being 'inspected', I am not aware of any inspector that has the time, or the authority to remove a device to check terminations. Perhaps there may be some, but none that I know.
Are you sure you aren't sharing a neutral on the same ungrounded side of the panel (Miswired multiwire circuit)?
John, I believe an inspector has the "authority" to inspect pretty much everything, time becomes the issue. When I was working travel was my biggest time burner so I looked a a lot of things that surprised people. I was not going to drive 2 hours to look out the window of my truck I have had them pull a device if I saw something funky and if I found something wrong we were going to look at some more. I really had no time constraints tho. It was why I liked my state job and why I never looked for a muni job. I was doing 1, maybe 2 a day. Ten a month was busy for me.
When I do an inspection I start with the thing that's hardest to do in the toughest place to get to. If they did that right there's a very good chance they did everything else right and my day will be an easy one. If they screwed it up I know that I'm going to find lots of shortcuts and workarounds in things that are easier.
Yes the remodeling contractor did both back stab and screw termination, did not pigtail off, but that goes back to following older installs, the customer said the plug got hot and was arcing at receptacle, Dyson fan heater, 1500 watts
Oddly enough, 15 years ago an electrician I was working under told me just the same thing, except about junction boxes in 1-ph 2w circuits - it's usually the neutral that burns. I can't say much about that since thankfully I haven't encountered too many loose connections. This was in Europe (Schuko territory, i.e. no polarisation) so left vs. right hand couldn't be an issue. Besides, junction boxes use loose connectors, so no correlation either.
The biggest problem that I come across with overloaded neutrals results from messing up the phases. If the original installer used a shared neutral it will only carry the maximum load from a single circuit; but if the neutral serves more than 1 phase the neutral can be tasked with carrying twice (or even triple) of the current on a single circuit.
In a home 120/240V: Shared neutral circuit connected to Black and Red incoming lines. During renovation the Red ends up being fed from the Black incoming line. Shared neutral is now being expected to carry twice as much current as intended. Neither of the hot conductors is overloaded so the circuit breakers never trip. Neutral carrying twice the rated current overheats, causes fire, house burns down, bad day for everyone involved.
BTW - This has happened enough times (including fatalities) that there is a movement in the NEC to prohibit shared neutrals entirely.