Is there any way to use a UPS properly when there's no ground wire in the outlet?

I have a GFCI setup and an outlet with a ground wire but it's not a real ground (apparently; I don't quite understand GFCI). My UPS's that have a 'wiring fault' light indicate a wiring fault (lit up).

My UPS's will sometimes give out (and my computer's reboot), even on low wattage load (like less than 50%), and I suspect it's due to not having proper ground. But they give out even when there's no apparent surge/brown out, no thunderstorm, etc. Should that be happening? Would this not happen if the outlet were properly grounded in a modern way?


  • 1
    Can you trace where the "ground" from the receptacle/outlet in question goes to? – ThreePhaseEel Aug 29 '20 at 19:33

While a UPS, and many surge protectors as well, will show wiring faults equivalent to a magic 8-ball, a UPS should never actually use ground, except if there is a true fault. A brownout or blackout should trigger the USP battery/inverter but not actually put any current on the ground wire. In fact, if it did then it would immediately trip the GFCI (assuming that some of that current should have been going on neutral).

More likely is a faulty UPS. The most common fault, unless it is brand new, is a battery that no longer holds a charge properly. UPS detects fault, switches to battery/inverter and promptly fails. Most small UPS now have user-replaceable batteries, though whether that makes sense or not depends on the age of the UPS (other parts can fail over time) and whether it might be time to upgrade to a larger UPS for other reasons.

  • Thanks for answering. The one UPS is quite new and only runs at 50% wattage load, while another UPS I have often runs close to max wattage (but not all the time), and the weird thing is they both exhibit the same symptom: It's like they just randomly give up for no apparent reason and drop out causing the computers to reboot. – Shovas Aug 30 '20 at 16:55

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