Anyone know what the standard back up time is for a "ups" serving a 3600 wt. load with 120 volts input and output, or maybe know a site that shows some models? I have a customer that has two pieces of equipment in an X ray dept. and he wants "ups" back up. The name plate on each, calls for a 15 amp. circuit. I didn't see the actual amp draw. These machines work together, and are at the present plugged into a 15 or 20 amp. recpt. That's the reason I doubt that they pull 15 amps apiece, because they would have already tripped the breaker. Any help would be appreciated.. Thanks. Steve