I just put in a new 220 circuit to run a rackmount UPS for some servers.

However, there are some issues with the ups, and it notes that the input voltage is only 200v, versus the expected 220v.

This plug is the only one present in the circuit, and I am fairly sure it is wired correctly. What could be the cause of the low voltage? Is it something that can be tweaked in the meter by an electrician? Is it something I need to bring up to the electric company?

I also realize it is somewhat normal to have variances in voltage, and shouldn't expect exact numbers. I wouldn't care if my ups didn't seem to. 20v seems like a fairly significant dip in voltage to me anyways though.

I am in a single family style home, 200a service in central PA

Checking across terminals within the panel:

  • both leads from breaker read ~113-114v from terminal to neutral bar, despite status of ups (not plugged in, plugged in and off, plugged in and on)
  • same reading from plug, except from hot plug to ground
  • same readings from other breakers
  • same reading directly from hot bar to neutral
  • reading from hot to hot on the breaker and plug is 225

So I might actually have a bad ups...

  • Where in the country are you, and is this in a house or an apartment building of some sort? Also, do you measure ~200V at other 220V (really, 240V) receptacles, such as a range or dryer receptacle? Nov 27, 2021 at 20:24
  • By "I just put in", do you mean that you did the work yourself? I'd ask you to double check that voltage (you could just have a faulty UPS) but it's not clear if you have the ability to do that.
    – Olivier
    Nov 27, 2021 at 20:24
  • Updated with house details, I did do the work myself to add the circuit/ plug, and have not checked with a voltmeter, will check when I get home
    – Snappawapa
    Nov 27, 2021 at 20:36
  • There are several possible causes. Check the supply voltage, and the voltage at the outlet with and without the UPS connected.
    – Simon B
    Nov 27, 2021 at 21:09
  • Most times people "talk" about 220 or 240 the supply is usually 230V with a tolerance of +10% and -6%. details actually found when you read contracts and / or have to deal with the Elec Company Engineers when generating from your site with a wind turbine for example.
    – Solar Mike
    Nov 27, 2021 at 21:12

1 Answer 1


ANSI C84.1-2020 American National Standard for Electric Power Systems and Equipment allows two standard levels of service, Range A being the normally acceptable 5% loss at your service, and 10% percent voltage loss at point of use, and Range B allowable voltage loss of 8.3% at your service and 13.3% percent voltage loss allowance at point of use to deliver acceptable performance.

Your single family residence should be served by a 120v/240v service, calculating a minimum service voltage of 220v and a minimum point of utilization of 208v.

Voltages at the service are utility responsibility, and if acceptable at the service the utilization is your responsibility. the 114v you have is right at the bottom of Range A, it is unlikely you would get any satisfactory response from your utility unless you can demonstrate times of day that unacceptable levels frequently occur.

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