Odd site wiring fault issue

[BillP]

Hello all,

In my server rack I have two older SU1400RM2U UPS units running at 120v. Both are 15 amp units. I just added a SUA2200RMXL3U which is also 120v but has a 5-20P plug. All have AP9617 cards installed for diagnostics and management. The two SU1400 units show no faults but the SU2200 unit has the site wiring fault LED showing red. All are plugged into the same quad gang wall outlets. Aside from having an electrician come into examine the wiring, which is obvious and most likely what will need to happen, might anyone have an idea as to why the 15 amp units show no fault but the 20 amp one does?

Thanks for any ideas.

Matt

[BillP · Accepted solution]

Are they all connected to the same electrical circuit? Sounds like the answer is yes? Because each UPS should be on its own electrical circuit generally..

If it is an overloaded neutral, each UPS may have slightly different criteria for illuminating the LED (maybe anywhere from 3-8V). The voltage on the overloaded neutral actually illuminates the LED if that is the cause of the site wiring fault. If you have a voltmeter yourself, you could check that without an electrician probably.

Other than that, it could also be a loose ground on the UPS side as well versus the outlet but usually jiggling the input cord on the UPS makes it flicker if that is the reason so you could also try that before you call an electrician.

Beyond that, then I am not sure besides having the electrician check it.