So I'm no electronics expert, but I assumed that any UPS that I bought at best buy would be suitable for home use. I bought an AOC XS Series (model BX 900R). It's specs are 900 VA / 540 Watts. As soon as I plug it into the wall the breaker for that room trips. I've tried multiple rooms and breakers, and it trips every single time.

How do I determine what's coming out of my wall, and how do I use that to figure out which UPS to get? Can the power coming to my outlets be changed easily by an electrician?

Are the tripping breakers ARC fault breakers?  They can be a major pain in the butt.

when you plug the UPS into the wall, what is plugged into it?

first i would take the UPS back to bestbuy and get a new one

if the new one does the same thing, i would figure out every device on that circuit, easiest thing to do would be flip the breaker off and see what loses power. make sure you aren't overloading the circuit which will usually be 20A. try unplugging any high draw devices (fans, things with motors, stereo equipment, certain types of lighting [fishtanks])

i find it really hard to believe that UPS could overload the circuit like that unless it is defective, UPS are basically glorified power strips that trickle charge a battery. the most sophisticated part of the UPS is the circuitry that monitors for b;lack/brown out conditions.

Thanks for the help guys.


Just looked in the breaker box, and the two rooms that I tested the UPS in both have ARC fault breakers. Any way I can work around them? I plugged the device into a room without at ARC breaker and it appears to be working fine.



Nothing is plugged into the UPS when I test it. I've tried with nothing else in the entire room plugged in as well.

Anyone know anything about ARC breakers?

UPS's use rectifiers that play hell with a sine wave and ARC flash breakers use solid state electronics, it's not beyond the realm of possibilities that the UPS's rectifier is distorting the sine wave enough that the breaker thinks there is an ARC or a ground fault.   A lot of ARC fault breakers have ground fault protection built in by the way.

Take it back to Best Buy and get a new one.  Try the new one in a plug that doesn't have an ARC fault breaker.

The unit I have plugs into a plug that does not have an ARC fault breaker and is working fine. It's only when I plug into ARC plugs. Also the ARC breakers are 15A whereas all of the other breakers are at least 20A.

Can I simply replace the 15A ARC breaker with a standard 20A?

I would replace it with a 15A breaker.