This reply was originally posted by Michelle on APC forums on 12/31/2016
I think I can answer my own question. I ran a 30A generator feed (2 x 10AWG) via EMT using the top 1/2" hole, on the right side of the main board, passing by the logic board and to the terminal block (bottom right).
There had to be some sort of emissions back fed from those wires that caused interference as it passed by the logic board. This made sense as a restart of the APC cleared the issue, but only temporarily. Once moved the EMT (and conductors) to the bottom right 3/4" hole (and not passing by the logic board at all), the problem went away.
The APC had been mounted for over a year with no issues, and the generator fed the APC out of the back (into the garage where the generator usually was). We had concern over the carbon monoxide running the generator in the garage, and decided to run 40ft of 10/2 cable to our back stair where the generator can sit outside (and well vented).
