I also have a Brother multifunction laser printer and it does make my lights flicker when I turn it on. Been doing it for years with no problems.
I don’t remember if it was in the printer documentation or in the UPS documentation but I recall reading somewhere that a laser printer should not be connected to the UPS – something about the quick surge of power overloading something.
The reason why was provided. A UPS in battery backup mode outputs power so dirty as to be harmful to power strip protectors and small electric motors. For example, this 120 volt UPS outputs 200 volt square waves with a spike of up to 270 volts. No problem for any electronics. A problem for motors and strip protectors.
Flickering lights means a wiring problem. All wires (even 1930 house wires) are so large that no flickering should occur. Not even with a laser printer. Fix the problem. Do not cure the symptoms.
No, this is not the reason.
Printer manuals say not to put printers on UPSs because:
The flickering is normal, if annoying. As I mentioned above, it’s such a common issue that the EU regulates it.
Flickering can occur on perfectly sound wiring - so I wouldn’t listen to the “experts” here who say you have a wiring problem. It’s not impossible, but having flicker due to a laser printer is not a definitive indicator.
Those are other reasons for not putting a UPS on the printer. The reasons are numerous. Another reason is that AC line anomalies are not eliminated or filtered by a UPS as hearsay claims. But the most important reason is because UPS power in battery backup mode can be harmful to some printers - especially laser printers. As defined with numbers.
Meanwhile, light flicker should be so minor as to not be noticeable. If one notices light flickering, then fix the actual wiring defect. Most often only a loose connection. In some rare cases, an indication of something that will eventually create a house fire. Especially if the flickering occurs on other branch circuits.
No acceptable reason for any printer to cause lights to flicker. Worse is to cure that symptom with a UPS.
Wrong, as usual.
ETA: a document discussing flicker.
Flickering that most people will notice is well beyond the “borderline of irritation”. Such trivial flickering is single digit voltage variations. Flicker that people actually notice is due to tens of volts variations. That much flickering implies a wiring problem. For example a loose wire to a wall receptacle. Easily located and fixed. Then a printer need not cause voltage to drop by tens of volts.
Your charts simply agree with what I have posted.
Sometimes that tens of volts variation is created by a human safety problem. Rare. But a layman is sadly advised to ‘fix’ it with a UPS. Instead, fix the problem. Never cure symptoms with a UPS. Especially when the solution is so easy.
Meanwhile, a UPS can also be harmful to the printer. Numbers provided previously. Just another reason why the UPS is poor and ill advised solution.
14 gauge wire has a resistance of .00297Ω/foot. For a run of 30 feet that’s (.00297 x 30 x 2) (the two is for both hot and neutral), or .1782Ω. If the printer fuser draws 1,200W, that’s 10.9A of current. V = IR, so the voltage drop will be 10.9 x .1782, or 1.94 volts
Incandescent lamp power is proportional to the square of the voltage.
So, having a 2 volt drop on a 110v line (110v going to 108v) will result in a (110^2 - 108^2)/(110^2) = 3.6% reduction in power, and an even greater reduction in light, which is easily noticeable.
Study this chart.
http://www.lamptech.co.uk/Documents/IN%20Voltage.htm
I repeat: THERE IS NOTHING WRONG WITH HER HOUSE WIRING!
(of course, I’m not clairvoyant - there could be something wrong, but a laser printer that causes flicker doesn’t mean anything)
I mean, cripes, I get a brief flicker when I turn on my stereo receiver, yet all my circuits are fine.
I think part of the problem here may be semantic. It appears the word “flicker” means something different to those in the trade than it does to all those people posting that their lights “flicker” when they turn on their Brother laser printer.
It looks like flicker is being used by professionals to indicate an ongoing condition in which the lights continue to flicker.
A better terminology for what I experience (and, I assume, others who have the same thing) might be to say “When I turn on my laser printer my lights dim momentarily and then come back up to normal.” They do not continue to flicker.
If your UPS is actually outputting 270 volts peak when 120 v is expected (peak voltage 170 v), then it most certainly would be bad for anything, electronics or not. Why? Many devices designed for 120 v only operation with switching power supplies use filter capacitors rated at 200 volts - 270 volts would blow them (note - computers and other devices with a 115/230 switch use a doubler in the 115 position, which is just two half-wave rectifiers feeding 200 v capacitors, often with ~200 v varistors across them). A well-made UPS, even of the simulated sine type (stepped square wave) should output a peak voltage of 150-170 v with a pulse width giving an RMS voltage of 110-120 v.
As for the lights flickering issue, I notice it all the time, especially when I draw a heavy amount of current; I can see incandescents dim with loads as little as 200 w, especially if it is a non-PFC SMPS due to the high peak current draw at the voltage peaks, which causes a noticeable flattening of the waveform on an oscilloscope (thus why countries like the EU require PFC for power supplies above 75 w; it isn’t required in the U.S. but I use it anyway in larger power supplies to reduce effective current draw). Many devices will also cause a brief dimming when plugged in or turned on as the capacitors charge (there are ways to reduce this by adding an inrush limiting circuit, usually nothing more than a thermistor though). However, I have never seen it adversely affect the operation of anything else on the circuit.
Dimming might be traceable to wires not properly twisted inside a wire nut. Or wires attached to a receptacle using the unreliable back stab method. Latter can be identified by inspection by any layman. Simply remove the cover plate. If wires are not securely attached to side mounted screws, then wires are using unreliable back stab connections. That would account for unnecessary dimming when the printer powers on.
However some dimming is due to a slowly getting worse human safety problem. For example, one homeowner ignored dimming since others told him it was normal. Eventually the problem became so bad that electricity used gas pipes as a conductor. Until a gasket failed. Fortunately nobody was home when the house exploded.
Dimming is a major concern if a building uses aluminum wire. Many should remember the over 100 killed because dimming was ignored. Resulting is one of the worst fires in Cincinnati history.
Those human safety threats are rare examples of a problem indicated by dimming. Two reasons why we fix simple wire problems rather than cure a symptom with a UPS.
Noticeable flicker should not exist because household wires are so thick; so conductive. That dimming implies poor wiring practices such as not twisting wires together or using back stab connections. Both are legal. Just not done by better electricians. If dimming (or brightening) occurs on other branch circuits, then be more concerned. If the building used aluminum wire, then fix the problem without delay. Do not consider a UPS to mask a compromised wire connection. Solve the problem; do not cure symptoms. Especially since most reasons are easily identified and eliminated.
No, if you read previous posts, even a small change in voltage will significantly affect the brightness of incandescent lamps, and wires certainly do not have negligible resistance. A voltage drop of 3 v or so from a 1 kW+ load isn’t uncommon (about what I measure in my work area when 15 amps are drawn and the lights noticeably dim, this is on the other side of the house from the service panel so it sounds right), and while that sounds small, the brightness of an incandescent will decrease by about 10%. Also, power supplies, even relatively low power ones, can have enormous inrush currents:
100 amps, even with a wire resistance of 100 milliohms (less than the example **beowulff **gave) will cause a voltage drop of 10 volts, and reduce brightness by about a third (link posted by beowulff). Note that inrush current levels don’t increase much with higher loads due to voltage drops and AC impedance (faster current changes are opposed more by inductances), so a laser printer may still have the same inrush current (it also depends on whether it has a resistive or lamp heater, the latter drawing about 10 times its normal current during inrush; a resistive (nichrome) heater will have nearly constant resistance whether hot or cold, the 10 amps or so may still cause a noticeable drop).
Also, there is voltage drop due to more than just household wiring, such as the resistance (and impedance, again due to stray inductance) of the step-down transformer to your house, transmission lines to the substation and so on (as an experiment, take a simple wall transformer (AC output) and measure its output while applying its rated load).
Note again that this assumes the lights just dim once for a fraction of a second, as opposed to actually flickering like a candle, which almost certainly would indicate a wiring problem (or a very dirty/inconstant load, but a printer shouldn’t do this).
Which is why we also see incandescent bulbs dimming 120 times a second. The assumed 100 amps are so short as to be almost unobserved. A 10 volt drop results in dimming (at 78%) so short that it is not noticed.
Startup current, in reality, averages much less. In a few locations, we identified the wiring problem, fixed the loose connections, and the dimming was eliminated.
So you are recommending a UPS? You advocate curing symptoms? Dimming is easily solved by fixing weak connections. And performed because sometimes (rarely) noticeable dimming is traceable to a major human safety problem - ie aluminum wires. Or do you advocate ignoring potential human safety problems?
You are not going to convince me of a reality that I have already solved with numbers and then solved by doing it. Printers that cause noticeable dimming were on circuits with poor wire connections. Fixed the connections. No more dimming. Been there. Done that. Multiple times.
So how often do you use a UPS to solve dimming created by a printer? That is the topic here. Please address the topic. Or tell the OP he should ignore all dimming.
A quick update, of sorts: The printer usually (but does not always) causes the UPS to click once (or perhaps twice), when it’s first turned on or a print job is sent for the first time in a while. The lights do flicker typically once, and then again maybe a minute or so later, but are otherwise fine.
The general household wiring: well the place is 15 years old. As far as I understand it, aluminum wiring was NOT commonly used then, but I wouldn’t rule out the possibility that there’s some in the house - we have trouble with a couple of the ground-fault interruptors going off at random times. This is a reminder that we really want to invest in a whole-house electrical system inspection.
The chance of you have aluminum wiring for anything other than range or dryer circuits is nil. As I (and a number of other posters) have said, this behavior is really common for laser printers. I’d just put up with it, or put it on it’s own circuit.
I don’t think aluminum wiring was used in construction much past the early '70s. It’s still used in distribution wiring (the stuff outside up on the utility poles) because aluminum has a better conductivity-to-weight ratio than copper.
A UPS is not a reliable indicator of low voltage. A UPS is typically made as cheap as possible. That means it may switch to batteries even when voltage is not too low. Even noise can make a UPS think low voltage exists.
If light dimming is so much as to be noticeable, then usual suspects include any receptacle in that circuit connected by the back stab method. Its wire not properly wrapped around the receptacle’s side mounted screws. That defect can be seen by only removing a cover plate; an inspection is that easy.
Aluminum is good for electrical wiring IF the installer has a right attitude. If the installer has proper training. Aluminum wires inside a house were problematic because too many electricians did not have the proper attitude and knowledge. Combine that with homeowners who think dimming lights are acceptable. Then conditions are ripe for house fires. Copper wiring is more forgiving of defective installations.
Status update: we had an electrician out this morning to do a general check on the household wiring. He did comment that a loose wire might cause the flickering. He checked and while the outlet was wired in a lazy manner (something about just through the holes in the outlet box vs. wrapping around the screws), it wasn’t anything dangerous.
He checked the other outlets etc. on the circuit and they were all the same, no danger. He did find a loose wire in one switchplate - he thinks that when they were stripping it to do the wiring initially, they may have nicked the wire, making it more likely to come loose. He fixed that, as it could ultimately lead to arcing, heat and pretty flames.
He told a story of one time where the homeowners had ignored flickering lights in one room, and when he got there and got the switchplate off, he saw - briefly - that the wires were red hot. Then they burst into flame. :eek:. Our printer issue is NOT the same thing - it’s flickering caused by a very specific thing, and is not a danger - just an annoyance. Of course it may shorten the life of the CF bulbs we have on that circuit.
We can have a dedicated circuit run for the printer, and we’re actually considering that but may not bother.
I also pointed out our oven. He was surprised that the oven and cooktop were on the same circuit, apparently that’s not usual (it’s a symptom of the mass-produced, throw-'em-up-in-a-hurry building style around here. The thing that DID concern him was that the power feed is heavy-gauge aluminum, which is permitted for that kind of use - AND that it was joined to the copper feed for the actual oven by an incorrect connector. It’s held up, and isn’t an immediate danger, but he suggested we might want to run copper for it when we’re having the oven replaced (in 2+ weeks).
So, we’ve scheduled that for the day before the oven comes - we’re home that day anyway and can help him wrestle that 200=pound behemoth out of the wall to get to the wiring.
I assume that the upshot of your electrician’s visit is: all problems have been fixed, and your printer still makes the lights flicker, right?