[gridley]

I'm not an electrician, but as I understand battery backups, it sound like the back up is working fine since when you unplug the unit, the backup kick in. I am wondering if, like you are wondering if there is an issue with the power bar or possibly with the wiring in the house. if you have not already tried this, I would try a different powerbar or plug the unit directly into the outlet and then turn off the breaker to that outlet - that will simulate a power outage, and see what happens. Good luck.