Dual fed UPS question.

[chevyx92]

What's the purpose of two feeds from same panel to a UPS cabinet? I recently saw a UPS fed from an MDP via two different circuits. One feed was a 350A 480V labeled "UPS MAIN FEED" and the other circuit was a 300A 480V circuit labeled " UPS BYPASS FEED". Why the dedundancy from the same panel?

 

[__dan]

It's not a dual feed. Dual feed would imply, or require, that the alternate feed is isolated and unaffected by outages on the primary source. For example, taking down the upstream supply to work on it would take the entire panel down, so it's not dual fed.

Sounds like they are using the panel breakers as part of the maintenance bypass for the UPS, with the bypass itself being another piece of equipment. With the UPS in bypass and the critical load fed from the "bypass breaker", you would open the UPS input breaker to take it down to work on it.