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Thanks for the help ahead of time. I'm not a certified electrician, but have VERY extensive experience working construction and repair. I do know quite a bit about electrical, but I'm not sure if I'm pushing my house breaker and fuses by doing what I'm going to do.

I work from home and need quite a bit of equipment installed in my office. I have an 850w computer and 5 servers in a cabinet that I want to install. I also have a window A/C unit. This is all running on 110v wall sockets. I have the A/C unit on its own socket. I have the high powered computer running on its own socket, and I have one free wall socket left. There are two 8-port surge protectors in the server cabinet. I plan on using those both on the 3rd available wall socket.

Is this safe? Right now the computer and A/C aren't making the breaker hot. The do cause a minor light flicker when they turn on. Nothing too serious, but I don't want to set my house on fire. I also don't want to pay $1000.00 to run a dedicated breaker box to my office. Is there anything I can do at the panel to make this safer? Perhaps change the breaker and fuses to something that can handle more juice?

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    If your house wiring is properly installed then the circuit breakers are sized to protect the existing wiring. Do not increase the size of the breakers or your house will burn down. (If your house wiring is not properly installed then you can do what you want because your house is going to burn down anyway.)
    – A. I. Breveleri
    Feb 19, 2016 at 1:50
  • Is wiring a new pair of 20A lines really that much a problem in your house? That would solve your problems. You really do not want to overload your wires...
    – yo'
    Feb 19, 2016 at 11:08
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    If you have a source of 220V power somewhere, and the PSUs of the servers can accept that, running a 220V line may also be a good idea.
    – Simon Richter
    Feb 19, 2016 at 12:49
  • Reconsider having a new circuit or circuits run. A fairly beefy computer, 5 servers, and A/C is a significant investment in hardware and time. Running that implies that you're doing it for work or are a serious hobbyist. Invest in providing proper power to those tools of your trade on dedicated circuits. What would downtime cost you in money and effort versus the cost of a new circuit? What would equipment damage cost in the event of a tripped breaker or wiring issue?
    – Freiheit
    Feb 19, 2016 at 15:56
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    As @Tester101 pointed out, if lights are flickering when the AC kicks on, damage can easily occur to computers, shortening the life of the computers. If lights flicker that share that same circuit, get that AC on a new circuit. If lights flicker/dim in other parts of the house on different circuits, you have a bigger electrical issue. Good practice is to use a UPS(batter backup). If you are unable to fix the dimming, i would suggest getting something like an APC Smart UPS, it outputs a clean sine wave of power. They are expensive though.
    – dave k
    Feb 19, 2016 at 16:20

5 Answers 5

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First of all, if you are only getting 110V at your electrical outlets (i.e. "wall sockets"), then there is likely something wrong with your electric system. Most AC in the US is 120V or higher (+/- 5V).

Secondly, your outlets may ALL be connect to the same electrical circuit. You should switch off your breaker/s & test each outlet for power to determine which circuit each outlet is connected to. Then you must determine the breaker Amp rating for each circuit that is used by your equipment. Then you must compute the wattage that is available for each circuit (e.g. 120V*15A=1800W). Next you must ensure your peak wattage from ALL of the devices that you plan to connect to each circuit will not exceed the available watts for each circuit.

Re: "Is it safe"? If everything is functioning properly (no breakers are tripping) during the hottest period of the year, then everything will probably be ok.

re: "Is there anything I can do at the panel to make this safer? Perhaps change the breaker and fuses to something that can handle more juice?"

I recommend you DO NOT change the breaker or fuses because your wiring may not be able to handle the increase in current (which causes heat & insulation breakdown--which leads to short-circuit conditions & fire).

The best thing that you can do is balance your loads on multiple circuits (if you have them) & do NOT exceed your power limits for each circuit or your breaker/s will trip increasingly often, fail, & then need to be replaced.

If you don't have enough power, you will either need to replace some of your devices with lower power devices or get new power brought into the area where you need it.

hth, best regards!

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    110V is not a problem. Many people even refer to 120V as 110V regardless of what it is.
    – TFK
    Feb 19, 2016 at 2:43
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    I agree with @TFK I just refer to it as 110v, I'm actually getting 121 (Give or take). This was an excellent answer though.
    – cloudnyn3
    Feb 19, 2016 at 2:46
  • Of note, when I was in the Air Force, I vaguely remember a safety limit of 80% of the maximum rated power. This random forum has a post saying 80% is part of the (presumably) Florida housing code. That one's for a single device, but I'm guessing it's the same logic.
    – MichaelS
    Feb 19, 2016 at 7:48
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    @MichaelS National Electrical Code says that you size the circuit to 100% the non-continuous load, plus 125% of the continuous load. So as you can see, the 80% reduction, is only for continuous loads.
    – Tester101
    Feb 19, 2016 at 9:14
  • @Tester101: That makes sense. And now I see the answer specifies "peak wattage", which I missed earlier. On that note, "peak wattage" of a computer is typically less than the rating on the power supply, so something like this calculator can be helpful there. In this case, idle (continuous) power is typically much less than 80% of peak power, so a second calculation is likely unnecessary.
    – MichaelS
    Feb 19, 2016 at 9:30
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If there's room in the panel, you could run additional circuits. If not, you could install a second panel, or try and free up space in the existing panel.

If you have room for additional circuits, I'd recommend putting the A/C unit on its own circuit. Because through normal use, the A/C unit will introduce surges and noise on the line. This is undesirable on circuits with sensitive electronics such as computers, so you should avoid having the A/C on the same circuit, if possible.

If you're seeing dimming lights when the A/C comes on, it's likely due to voltage drop. This voltage drop is caused, because the A/C is drawing a large amount of current when the unit starts up. This drop in voltage can be damaging to sensitive electronics.

Depending on the load requirements of the servers, it may be desirable to install an additional separate circuit to handle them.

If possible; and depending on the load requirements, I'd recommend using three circuits. One for the A/C, one for the servers, and one general use circuit for the PC, monitors, and various other office equipment.

Installing a larger breaker is likely not an option, unless the wiring, devices, and equipment are all rated for the higher current (not likely).

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How much power does each server pull?

Regardless, to go ahead and plug it in. I'm glad that you're asking before the breaker trips, unlike many, but without knowing the load, this will essentially be your break point.

Currently you've more than likely got a 20A breaker. This means that the wires in the wall are rated to carry 20A and the devices on the circuit (the three receptacles) are rated 20A. The wires can carry a little more, but the rating of them goes with the idea that running them over their rated amperage for too long will cause them to burn up (same for the devices). This is where a breaker comes in. It breaks the circuit when it is trying to pull too much power so that you don't burn up the wires, you're devices, and potentially your house.

What I'm getting at, is that upsizing your breaker doesn't give you more power. It's not there to control the flow, your wires are, it's simply there to protect your wires.

The only solution would be to add more circuits or upsize the wiring, all devices, and the breaker. If your circuit can handle the load as is, you'll be fine. If not, you'll have to take one of these options.

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  • Is it feasible to locate the wires at both ends, and perhaps tie something to them at the breaker and fish them through the roof? I would assume wires handling 50A? I run CAT cable and we used this quite a bit. I don't know if that would work though. This is a mobile home, and I have NO access to the ceiling; I would literally have to use a wire detector and tear the walls out.
    – cloudnyn3
    Feb 19, 2016 at 1:51
  • You can use a tone generator to identify power cables, just like you do for comm cabling--however I would make sure to test every outlet because some circuits are branched off other circuits & that could definitely complicate your plans. You won't know for certain if you can use the existing cable as a pull cable for a new higher-rate cable until you try it. Some cables have too many corner bends &/or they are secured in place--so it may or may not work in your situation. Instead of tearing out the walls, you might be able to just lay a new cable inside the mobile home.
    – DIYser
    Feb 19, 2016 at 2:11
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Consider putting the servers in another room. One with separate circuit. Or, run a good quality full rated extension cord (gasp!) from another room.

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  • Not sure if you were being a troll lol, but thanks for the suggestion.
    – cloudnyn3
    Feb 20, 2016 at 19:39
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One possibility for freeing a little power in the room: Replace any incandescent bulbs with either CFL or LED bulbs that produce the same amount of light (while using less power). Replace any CFL or long fluorescent bulbs with LED bulbs that produce the same amount of light (while using less power). I doubt if this will free enough power for your situation, but it's something to try if some other method only gets close to what you need.

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  • The lights usually have a separate circuit, so that when you repair your outlets, you have the lights on, and when you repair your lights, you can plug a lamp in.
    – yo'
    Feb 19, 2016 at 11:06
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    @yo': Indeed; another reason for this is because you don't want to be in a situation where an electrical fault in, oh, I don't know, maybe the circular saw that you're holding right now also causes the lights to go out. Because then you'd be standing in the dark with a spinning, faulty power tool. You don't want to make the situation worse by cutting the power to the lights too.
    – Eric Lippert
    Feb 19, 2016 at 14:48

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