zbang
Senior Member
- Location
- Roughly 5346 miles from Earls Court
Yesterday, I was checking out why some data systems in a computer room weren't coming on. My handy T-Pro said that two of the UPS outlets have only 85 volts (that would be why), but the rest had 122. Hmm... it's a single phase UPS and doesn't have any alarms. Load wiring is all 120v 20a 1-phase from a single phase QO panel with 1p breakers.
Turns out that this UPS can be wired for either 120/240v or 208v single phase output... and 122 + 85 = 207. According to the manual, there's an extra tap on one side of the output transformer to get the 208 output and it seems like the original installer used it. Been like this for a couple of years, and most of the electronics just worked on the low voltage. I can't confirm the actual wiring until a shutdown next week, but I'd put some money on the cause of the problem.
Makes me wonder if whoever did the load wiring even bothered to check their work (or to care about it). I'll be giving it all a good going-over.
Turns out that this UPS can be wired for either 120/240v or 208v single phase output... and 122 + 85 = 207. According to the manual, there's an extra tap on one side of the output transformer to get the 208 output and it seems like the original installer used it. Been like this for a couple of years, and most of the electronics just worked on the low voltage. I can't confirm the actual wiring until a shutdown next week, but I'd put some money on the cause of the problem.
Makes me wonder if whoever did the load wiring even bothered to check their work (or to care about it). I'll be giving it all a good going-over.
