Redsy;
Thats an ingenious idea to back feed the circuit and look for the open. When the open is intermittant like that and the panel checks out ie breaker is ok and the neutral is ok, then the only other thing to do is to open every box and check the devices, I have found since the advent of back-fed devices that a lot of new homes are made up that way. There is only a point contact when a receptacle is wired by back-feed and with heat and use the spring tension becomes lose and an open can occur easily and re-weld itself back together. Out of desparation I will take a rubber mallet and tap next to all the offending receptacles and someitmes you can find the offender.
The good news is that 95 % of those problems are indeed in a box but if you have a burried JB then thats a problem.
You say the carpenter did it, i wish that was always the case. Had one addition that the Ahmish built and they wired it too, talk about a nightmare I wound up rewiring the whole addition, but thats another story.
