Can Running a Server's Redundant PSU on Different Circuits Damage It?

So I've been tasked to document and review the status of the UPSes for my current employer and identify any changes that need to be made. Generally easy stuff, however I came across a few units that are plugged into both regular power and a UPS outlet. I've done similar before but it reminded me of an electrician I used to work with who said doing this could damage the equipment.

I've been looking online to figure out what the specifics of this warning was about, but I haven't found much. From memory, I think it had something to do with using circuits from different sources provided by Three-Phase power. I was working on industrial sites at the time, and some power was provided to my servers by three-phase transformers. Not all was, however.

My question is: Are there any instances where running a system with redundant power supplies could be damaged by running them on different power circuits, assuming both circuits are clean (eg, running both PSU on either circuit alone would cause no damage).

Thanks,

With multi-phase AC systems (motors, etc.), you're right, bad things can and will happen if one of the phases drops out. However, with computer PSUs, each of them operates completely separately, converting its AC input voltage to a variety of DC voltages for the computer system.

You can safely run redundant PSUs on different circuits, different phases, etc. Doing so is actually a really great idea to reduce the number of components that are fate-shared.

The job of the power supply is to take power that is not 100% clean and make is stable.

People working in data centers have been fired for not having the power supplies run on different circuits. If one circuit breaker goes off, or one UPS dies, the whole server goes down which is not the intended design.

Ideally you would want them on separate circuits on with a different UPS on each circuit so that if anything goes down the server is still good to go.