I saw that thread and I wouldn't touch it with a 10' hot stick. When you add unqualified people to the mythology that has come up around AFCIs there will be no winning that fight.
I agree this is probably a neutral problem but finding it
is beyond the capabilities of the OP.

BTW I had my neighbor call an electrician the other day myself. He was tripping the breaker for one of the kitchen SA circuits with the GFCI tripped and I knew it had to be something strange. Above my pay grade. I am just a lowly inspector and I just knew there was a violation wink
Turns out they had grabbed that circuit for the dock receptacle on the line side of the counter top GFCI.

This is the same guy who had the dead receptacles I wrote about in the spring. That turned out to be a GFCI behind a cabinet in the garage (that he swore wasn't there).
I did have the right wall where the "buried" box I suspected, was. He swore up and down that GFCI was not there when he put the cabinet there.


Greg Fretwell