Powering redundant PSU with split-phase power

[NB2020]

I have a quick question about powering servers with redundant PSU. I'm based in the US, in which electricity comes into the home as two 120v hot wires and 1 neutral. The two 120v wires are out of phase, meaning one is at 120v and the other at -120v at the same point in time. The documentation for some smart home automation systems mentioned that their systems must be powered from the same 120v wire, and that mixing them will cause issues.

Can anyone more knowledgeable than me let me know if this is a concern for typical home servers? In other words, can I connect one PSU to an outlet from one of the 120v wires, and the redundant PSU to the other 120v supply? In the case of a PSU failure and the server takes power from the other PSU, I am wondering if there is any concern to the server operation since the new power would not be in the same phase.

There would be a UPS in between each of the outlets and PSUs, but I am too noob to know if the UPS "aligns" the power in any way.

 

[NablaSquaredG]

I have often powered servers with redundant PSUs from independent UPSes and never had any issues.

It's quite common to have servers powered from two independent power rails, which are most probably out of phase.

In other words: Go ahead.

 

[NB2020]

Ok, thanks for the confirmation. I just wanted to know if it would cause any hiccups during normal operation and failover.

 

[JSchuricht]

What you have is a single phase between two hot lines which creates 240v. The split is a transformer between the two hot lines that is center tapped and creates 120v. The issue some automation equipment has is that it is using the power lines for communication. Because the equipment is using only half of the phase, it only has access to a neutral and hot and if other equipment is using neutral and the second hot the communications may not work.

Using both half's of the phase to power separate power supplies is a non issue by itself. Two 120v UPS's isn't an issue either.

 

[NB2020]

What you have is a single phase between two hot lines which creates 240v. The split is a transformer between the two hot lines that is center tapped and creates 120v. The issue some automation equipment has is that it is using the power lines for communication. Because the equipment is using only half of the phase, it only has access to a neutral and hot and if other equipment is using neutral and the second hot the communications may not work.

Using both half's of the phase to power separate power supplies is a non issue by itself. Two 120v UPS's isn't an issue either.

Yea, I figured as long as the power is there, the phase shouldn't matter to the equipment but I wanted to be sure. The explanation for the home automation equipment makes sense. I didn't know they would use power lines for communication. The example I found was for panelized lighting and it mentioned that all of the breakers used for the light circuits should come from the same 120v leg. To me, it looked like all of the communication was done over mesh network, but there's probably some back-end communication going on that isn't user-facing.