I have a newly built 110V 20A basement office wired with 12/2 with eight T8 bulbs overhead, 850 watt PC, three LED monitors and a big Canon MF8380Cdw laser printer on the same aforementioned 20 amp circuit. Whenever the printer comes out of power saving, the lights all flicker and one or two monitors power off and back on trigger my PC to consolidate all of my windows on one monitor.

I am planning to add some additional home theater equipment to the office but I'm concerned by the laser printer interrupting it or worse, damaging it.

Is there any solutions to mitigate the power draw of the printer without adding another circuit or expensive voltage conditioning equipment?

Update 2: Office electrical during construction Power box is #1, then to light switch on to first outlet at #2, printer is at #3 and computer equipment is at #4. Wire from box to first outlet is approximately 32' Room is 18' x 11'.

Update 1: A lot of answers are warning against a UPS on the printer. I do not utilize a UPS at all at the moment. And when I do purchase one, I do not plan to feed the laser printer from it for obvious reasons. My power is otherwise very stable from a new square D box (in 2002-ish) and the meter and the lines feeding my house have been recently updated by the power company.

I've read in the reviews of this Automatic Voltage Regulator that people have used it for their laser printer to solve the brown outs. This would be cheaper than rewiring the office but obviously not solve for the lights. And this is a 10A device.

Per the pg17 of MF8380Cdw Printer Manual, the power supply requirements are 120 to 127 V, 60 Hz, 1,200 W or less

  • Just to clarify, your 20A circuit is using at least 12 GA wire correct?
    – bigbull15
    Commented Apr 25, 2016 at 18:13
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    The entire room is wired with 12/2, and is done to code as of 2014.
    – Josh Brown
    Commented Apr 26, 2016 at 12:19
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    if I were in your shoes, I would contact a reputable copy machine sales/service company and ask what they use to protect their equipment. I offer this as a suggestion, not an answer.
    – bigbull15
    Commented Apr 26, 2016 at 13:19
  • Get a kill-a-watt, plug the printer through the kill-a-watt into the outlet that is nearest to the box, and report voltage sag & current numbers you're seeing when the printer does its thing. Commented Apr 27, 2016 at 23:38

4 Answers 4


This is called "voltage sag". Short of sticking all sensitive equipment on a UPS, there isn't a lot you can do to combat it, particularly on the printer side. One thing you could try is to put a surge protector between the printer and sensitive systems. Some surge protectors may be able to suppress voltage sag, particularly the ones advertising as "line conditioners". There are specialized voltage sag suppressors out there but I don't think they are cheap or commonly available for office users.

In addition, try to rearrange your wiring to make sure that part of the circuit from the printer to the service panel that is shared with your sensitive equipment is as short and as thick (low gauge) as possible.

  • Based on what you've said, I've found this amzn.com/B00009RA60 "Automatic Voltage Regulator". Is this what you meant by "line conditioner"? The reviews have mentioned it helping with laser printers. And it is definitely the most affordable option I've seen yet.
    – Josh Brown
    Commented Apr 26, 2016 at 14:26
  • Yes, give that one a try. Commented Apr 26, 2016 at 17:52
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    That's a "line interactive" UPS, just without the UPS part. That will make things worse. These devices work by changing taps on a transformer, which means when voltage sags, they will draw correspondingly more current to compensate. This will sag voltage even more. Since switching power supplies also tend to do this, you're now in a race condition. So far your saving grace is that the fuser backs off, being a linear load, and the monitors cut out. Commented Apr 26, 2016 at 19:01
  • If you want to buy big transformers, there's another way to skin this cat. Commented Apr 26, 2016 at 19:03
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    Well, that's what did it. You moved the printer to the outlet next to the service panel. That's on a different circuit. Your problems are solved. You don't need the line conditioner, send it back, keep the $. An outlet right next to a service panel is almost always on its own dedicated circuit breaker - electricians put them there to power their tools while wiring or troubleshooting the house. It's perfectly fine to use it. It's an excellent solution. Commented Apr 29, 2016 at 20:29

Since you've posted a lot more info, I'm editing my answer to suit your need and those who might have a similar issue in the future.

TLDR: You have good electrical, you just overloaded it. It happens.

The crux of the problem is you were overloading a single branch circuit. You've got continuous loads of 6-10 amps (computer), three 0.5-1 amp (A) monitors, at least 2A of lighting, so 9.5-15A. So far, within the range of a single 20A branch circuit.

The printer, however, pushed your good wiring past design limits. The printer claims 10A draw while underway, which means drawing up to 25A on a 20A circuit. But fusers often have a fraction-of-a-second inrush current of 20A or more. This guaranteed a brownout on any single 20A circuit, and risked a breaker trip.

When you revised your question, you showed us pictures and diagram of the site. There's an outlet right next to the service panel. Electricians typically install those to power their own tools while wiring the house, and they put them on a separate circuit. Moving the printer there is a good permanent solution.

Now, how do you catch this in the future? Get a $20 Kill-a-Watt power monitor. It lets you measure each load (in turn) so you can definitely know the current each appliance draws, and plan circuit balance. It will also show voltage sags, which combined with the known current draws make it easy to distinguish a true overload from a too-long wire run.

When you simply need to draw more power than a circuit can handle, there is no gadget which will let you do that.

  • Not Surge suppressors. They limit voltage surges, not voltage dips.

  • Not automatic voltage regulators or line-interactive UPS's. They make things even worse, by drawing more current still to compensate for lost voltage. They are intended for cases where the utility company cannot provide full voltage to your house, and your branch circuit has extra amp capacity. They should never be used to correct voltage sag in an overloaded branch circuit.

  • Not UPS's. You might think a UPS could store power to help bridge across short-term overloads, but as a practical thing, no. That's not what they're made for.

The tech that works is plain old copper wire. Installing wire is a very learnable skill for tech types, and it's shockingly cheap. The cost is in the labor, which can be considerable if it's behind finished walls.

If you have no other option, there's a bold trick that lets you double a circuit's capacity: Re-designate the circuit to be 240V. Keep the wire, change all outlets, the breaker, and any fixed appliances like lights. Some of your gadgets are already multi-voltage (120-240V). For the rest, use a transformer. For wired-in lighting, disconnect or make sure the fixture is rated for 240V, and use multi-voltage or 240V bulbs. For fluorescent lights, most new ballasts are already multi-voltage 120-277V, check yours and replace ballast if needed. While complicated, this is a solid and safe solution to a hard problem.

  • I'm not sure why a UPS on a the printer keeps coming up but that's not going to happen. And I'm definitely properly wired for 20A. It would be prohibitively expensive to add a new circuit just for the printer. Offices often have laser printers and copiers near their PCs all the time without issue. I'm only planning a TV and a sound bar, but do not want to risk damage to those.
    – Josh Brown
    Commented Apr 26, 2016 at 14:24
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    I know, I'm trying to quell this "UPS" thing :) Ok. So the circuit is tip-top. That leaves either terrible monitors, or overloading the circuit. My back-of-napkin says you are already near circuit limits without the printer, but a $20 Kill-a-Watt will tell. By comparison, offices have multiple circuits and facilities departments bird-dogging load, and any printer this big is networked, so it sits where the power is. Office PCs are also like 100W with little Intel 4000 VPUs, partly for this reason. Commented Apr 26, 2016 at 19:47

That is a feature of laser printers - they work by using heat to fuse plastic toner onto paper. That usually means a periodic very high current draw.

I think your main choices include

  • Replace the laser with an inkjet
  • Try a borrowed different laser printer
  • Buy a very small inexpensive UPS for the computer and monitors (not for the laser printer).

Some manufacturers give both average and peak power requirements for their laser printers, you might use this to select a new laser printer that is less likely to cause the same problems.


  • Replacing the laser printer is not an option. Your idea of using a UPS sounds ideal of those three options but it sounds like I'll need one for each location that I have equipment that I need uninterrupted. I can certainly consolidate the TV and sound in one area and office equipment in another. But solving for the printer would be ideal if possible.
    – Josh Brown
    Commented Apr 25, 2016 at 16:51

The problem is that some laser printers try to fast start their fuser by allowing maximum power on start up. This makes the printer ready faster but induces a high "inrush" current which can be at least 20 amps and sometimes as much as 40 amps momentarily.

Do not use a UPS on a laser printer. UPS's are for computers. Your printer instructions should specifically warn not to use a UPS on the printer. The reason is that high current draws can damage a UPS.

Use a good quality surge suppressor to limit the current to the device.

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    I'm curious how a surge suppressor will help with the inrush current. I've been unable to find any reference to one limiting the current that something is drawing. Would this result from using a 15A suppressor on a 20A circuit? This sounds like the best possible solution but I need to understand it a little better.
    – Josh Brown
    Commented Apr 25, 2016 at 17:02
  • @Josh: See Surge Suppressor they mostly protect against transient overvoltage (e.g. induced by nearby lightning strike) not against transient undervoltage (sag) Commented Apr 25, 2016 at 23:10

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