I have a LOT of computer equipment in my bonus room. Additionally, during the summer, our HVAC system has difficulty keeping it cool (as a side note, the HVAC was replaced recently, so it is not defective - just your typical issues with a zoned system in the dead of summer).

During the summer I use a portable air conditioner to try to keep from roasting. However, with all my equipment running, adding in the air conditioner will frequently trip the breaker, which I believe is a standard 15-amp.

If I wanted to upgrade the circuit to 20 amps or higher in order to sustain the load, I suspect it would take both a new circuit breaker and rewiring the outlets with heavier gauge wire, correct? Anything else?

  • 5
    you could run a second line from another (new) breaker to the room it's simpler and color coding the outlets will let you balance the load more easily (and you can get up to 30 amps instead of only 20) Jan 11 '12 at 0:18
  • Not sure how much stuff you have -- but do you actually need it all in that room? If you can relocate some things to a basement/crawlspace and just run the wires you need, you not only avoid the heat, but also lower the noise and free up space. Gigabit network is a start, but you can also get KVM extenders, long video/audio/usb/HDMI/etc cables (possible to do very long runs over Cat5), etc. Not much you can't do remotely these days.
    – gregmac
    Jan 11 '12 at 8:03

"Upgrading" the circuit involves running a new cable (of thicker gauge). Basically you would be replacing a 15 amp circuit with a 20 amp, for a benefit of 5 amps but with all of the work of just running a new circuit (either 15 or 20) which would give you a total of 30-35 amps instead of 20. Because you also have two circuits, if one blows, only loose whatever was on that circuit instead of everything.

Running a new circuit is the way to go. As a commenter said, you can "balance" the load. Ideally you would not have the AC on the same circuit as your computer as the motors can put off electrical noise.

The gauge of wire you use will depend on the amperage and distance. If your room is upstairs with the bedrooms, code will often require an arc-fault breaker to be used.

  • 1
    2008 code updated but not enforced by all municipalities:As of January 2008 only "combination type" AFCIs will meet the NEC requirement. The 2008 NEC requires the installation of combination-type AFCIs in all 15 and 20 ampere residential circuits with the exception of laundries, kitchens, bathrooms, garages and unfinished basements. Wikipedia Where I live I think 3 out of 7 towns are enforcing 2008 code on this with more to follow.
    – lqlarry
    Jan 11 '12 at 3:21
  • 2
    If you decide to run a new circuit, you could run a 240V 30A subpanel to that room, and then have all the power you could want, for only a little more cost & effort.
    – Jay Bazuzi
    Jan 11 '12 at 5:03
  • @JayBazuzi did you buy stock in a company that makes sub panels recently?
    – Tester101
    Jan 11 '12 at 13:03
  • You'd think so...
    – Jay Bazuzi
    Jan 11 '12 at 17:50

I agree with just adding a new circuit instead of replacing the existing one. If you do that, you might want to consider making it a 240 volt circuit. One plus with a 240 volt circuit is that the AFCI requirement does not apply. One NEC rule (210.6(A)(2)) does require the circuit be for no loads smaller than 1440 VA. You can get around this limitation with a UPS which is 1440 VA or larger. The "208" volt models would be the ones to choose.

This will double your added capacity. You will be limited to only running 240 volt devices. Virtually all computers handle either dual voltage by a switch, or an autorange from 100 volts to 240 volts. You'll still have the previous 120 volt circuit for everything else (but for best surge protection, do not connect anything between devices running on different circuits, unless it is an optical or RF connection).

The cost impact of a 240 volt circuit is the price difference of a 2-pole non-AFCI breaker vs. a 1-pole AFCI breaker (probably about the same), the panel space this new breaker takes up, and a few inches of marking tape to make the cable in the wall legal by wrapping black, red, or blue around both ends of the white wire (since it won't be a neutral on a 240 volt circuit).

A couple suggested UPSes for 240 volts:

For 2000 VA ... http://powerquality.eaton.com/PW9130G2000T-XLEU.aspx?CX=3

For 3000 VA ... http://powerquality.eaton.com/PW9130G3000T-XLEU.aspx?CX=3

If you choose these UPSes you might want the NEMA L6-20 "twist and lock" type outlet. Your electrician should know what "L6-20" means (if not, hire a different one that does). These UPSes give you 8 C13 type outlets that cords which plug into computer towers use, so all you need is to get some C14 to C13 power extension cords).

  • If you're going to run a 240V circuit, you could use an extra conductor (so 12/3 instead of 12/2) and get a 240V/120V circuit, which is much more useful. If you bump up to 10/3, you get a 30A subpanel out of it... more useful still. But I'm a subpanel freak.
    – Jay Bazuzi
    Jan 11 '12 at 6:16
  • All true. And you could add a surge protector to that subpanel and have everything connected from it all protected together the way surge protection is supposed to work.
    – Skaperen
    Jan 11 '12 at 7:01
  • And while you are at it may as well buy a large liebert UPS to power the whole place :)
    – Steven
    Jan 11 '12 at 17:54

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.