I managed to pick up a great deal on a CyberPower OR2200LCDRT2U UPS. Unfortunately this box has a NEMA L5-30P input plug (NOT a L5-20P as specified on the product page). In the location I'm trying to set this up, I only have a 15-amp circuit with a 15-amp breaker. Further, it's basically on the opposite side of the house from the breaker, so I suspect that running a dedicated 30-amp line would be prohibitively expensive.

Now I have found that there are adapters you can buy like this or this but I'm not sure if I am creating a fire hazard by using one. Will the breaker trip immediately if my rack draws more than 15 amps of power? Am I at risk of creating arcing by doing this?

I don't expect to be drawing anywhere near the maximum capacity of this system. Just looking to figure out if I'm out of luck if I don't have a 30-amp circuit already present, or if I can safely adapt down to a 15-amp circuit.

  • 1
    i only see in the images a 20A plug, which means with simple Eletrcictal Calculation (P=U*I) which means P=120*20=2400Watt and as i understand the UPS has 2200watt wich should fit in case that you dont overload it
    – djdomi
    Aug 18, 2021 at 16:53
  • 1
    Monitor the load of the UPS, don't plugin things that would result in a a load above 15A, or more safely ~12A. That UPS has load indicators, and I suspect can be monitored if you connect via USB/Serial. If load goes above ~1440W, then alert. Ideally if your 15A circuit has a breaker that isn't cheap shit, it will just break the circuit if you go to high anyway.
    – Zoredache
    Aug 18, 2021 at 17:29
  • 1
    @djdomi, they said the circuit was 15A. They shouldn't go above what the circuit can handle, so ideally they need to stay under ~1440.
    – Zoredache
    Aug 18, 2021 at 17:31
  • 1
    @Zerodrache 15*120=1800 which means basicly that theres a bit still free options. However the 30Amps will only be taken in case you are fully load the UPS
    – djdomi
    Aug 18, 2021 at 17:35
  • thank you for your comments...of course I will be monitoring the load, what I'm trying to find out is what happens if I do spike above 1800W: does that trip the circuit breaker or burn the house down? Big difference in consequences, that's all I'm trying to find out.
    – matoro
    Aug 19, 2021 at 3:24

1 Answer 1


While technically the UPS will not likely draw much of a significant load itself if there are no devices plugged into it to charge the battery/batteries, you would safely be under the limit of what the 15A circuit can supply. It is all the devices you plug into the UPS is what draws the maximum load from the circuit. Thus the rating on the UPS is for how much the UPS can handle under load. So if your devices are working fine plugged directly in the 15A circuit, you would not be drawing any bigger load by putting the UPS into the chain and it would be safe to use it that way.

However, the problem is that those connectors are used to guarantee safe usage when the load does get higher (you start adding more devices than you have now) and you are now approaching the limit. The breaker on the 15A circuit should trip way before you actually reach that high of a load, so again, you would technically be safe. But the big problem is that this would be a violation of electrical and fire codes in most places and if caught doing this, you could be subject to safety violations or fines. So do not recommend doing it.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.