Is anyone using a UPS (uninterrupted power source) to back up their critical equipment in case of a power outage? I looked at a number of them by CyberPower and the "best" residential unit would run my critical equipment for only 2 hrs. Commercial units with EBUs (extra battery units) cost $1000- $2500! Please let me know what UPS you're using, what your "critical" equipment is, and what your estimated run time is. Thank you.