Redundant Power Supplies and UPS (Dell Servers)

I can't seem to find this documented but my experience (with a clamp-on ammeter I might add) is that they do balance the load.

Both PSU's draw roughly 50%, and will ramp up as required.

The main reason to plug each PSU into a different supply is one of redundancy - if your UPS has a fault and stops providing power, then everything plugged into it is going to be affected.

If you have one PSU plugged into the filtered mains, then you are protected in both situations - loss of the UPS and loss of mains.

Thats a lesson I learned the hard way a few months ago.

I believe the draw is proportional to the load. So beware total loading -- if one UPS dies before the other, the survivor will have to be able to carry the full load on its own.

Learned that the hard way, myself.

its intended for redundancy. get a second ups and plug the second psu into it.