I recently installed a circuit for a new printer in an office. I installed a receptacle in the wall and tied in to the conduit that feeds the office lights, giving me an easy path to the electrical panel. I ran a new circuit in that conduit to a separate breaker. Whenever the printer starts printing, the office lights blink a couple of times. Was this a mistake installing the printer power in the same conduit as the office lighting ? Thank You for any information. Steve Wiese.
Printer causing office lights to flicker.
- Thread starter steve61
- Start date
- Location
- Illinois
- Occupation
- retired electrician
Being in the same conduit has nothing to do with the issue.
LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
While it "shouldn't" affect the lights, it apparently is.
You didn't share the lighting neutral, did you?
I suggest temporarily powering it elsewhere and seeing what happens.
You could be exposing a building service neutral issue.
You didn't share the lighting neutral, did you?
I suggest temporarily powering it elsewhere and seeing what happens.
You could be exposing a building service neutral issue.
LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
Even with the wiring randomly intertwined in the conduit and LED lights?
ModbusMan
Senior Member
- Location
- Cleveland, OH
- Occupation
- Building Automation Engineer
I'd be skeptical... it's not like 120v (or 208v) generates all that much EMF while traveling down the wire. If both were 277v then maybe, but I'd be a lot more inclined to believe an incorrectly twisted wirenut was jostled during the pull and is now making itself known.
gadfly56
Senior Member
- Location
- New Jersey
- Occupation
- Professional Engineer, Fire & Life Safety
ONLY when the printer starts up?? Unless the printer has a carriage that is jostling a wall, I'm skeptical about that.
- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
Haven't laser printers caused flickering lights, in smaller facilities, for the past 20 years?
ModbusMan
Senior Member
- Location
- Cleveland, OH
- Occupation
- Building Automation Engineer
Loose neutrals do all sorts of strange things, especially in MWBC situations (which wouldn't be the case for the printer itself, but could potentially be an issue on the lighting circuit).
LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
All good reasoning for a process-of-elimination troubleshooting.
hillbilly1
Senior Member
- Location
- North Georgia mountains
- Occupation
- Owner/electrical contractor
Yes, they have heaters that draw short bursts of current causing voltage drop. Especially if they are fed from a ups supplied panel.
hillbilly1
Senior Member
- Location
- North Georgia mountains
- Occupation
- Owner/electrical contractor
Lowes employees were bad to plug laser printers into “clean” power at the service and pro desks. I would get calls about the ups temporarily beeping on overload at a regular rhythm. Always a laser printer! LOL!
I actually have two identical printers right next to each other. Each is on a different circuit.(120 VAC,20 amp) I ran a separate circuit for one of the two since they both draw 15 amps each. Both work fine on the original circuit with no lights blinking. They both cause the lights to blink when powered by the new circuit that I installed.
The new circuit has its own neutral, no sharing of neutrals. I will check in the only two 4" square boxes in the conduit run. Time to start checking connections, splices, Etc.
The new circuit has its own neutral, no sharing of neutrals. I will check in the only two 4" square boxes in the conduit run. Time to start checking connections, splices, Etc.
- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
Are the problem receptacle and the lights on the same panel hot leg? Is the good receptacle on a different one?
ptonsparky
Tom
- Occupation
- EC - retired
You need to check the VD at the panel when the printer cycles. Make sure that printer is not on the same leg as the lighting. We know that LEDs are affected by very little VD.
ptonsparky
Tom
- Occupation
- EC - retired
Dad gummit, you were quicker on the return key!!
- Location
- San Francisco Bay Area, CA, USA
- Occupation
- Electrical Engineer
That was my first go-to. Might even just be the neutral in that circuit.
This is one of the modern ghosts caused by the intersection of newish technologies. Laser printers, digital toaster ovens, direct drive washing machines, inverter mini split air conditioners... All of these things drive LEDs crazy.
Flicker Index
Senior Member
- Location
- Pac NW
- Occupation
- Lights
I doubt sharing the conduit has anything to do with it, but you could attach a long extension cord into the breaker where you've installed a printer into and bypass the conduit. You're just substituting the conduit with an extension cord for troubleshooting. If shared wires/induced transient is the cause, this would resolve it.
However, more than likely, the cause is related to the way the printer draws power causing a few volts of voltage drops at the panel. Few volts, but very rapidly. You might get rid of flicker in one area if you re-locate the breaker, but simply move the flicker or other problems elsewhere. It all has to do with energy conservation features of laser printers so that heaters are not remaining on like a pilot light in an old furnace yet be able to start printing relatively briskly without delay.
It works like plugging a 20A load into an outlet and very rapidly cycling it. (ignore the vertical scale... the pulses of real printers are often 15-20A). Even if the ballast is rated 120 to 277v, that means it will operate at the same power with gradual input voltage change. Not that output won't flicker at very abrupt notches. The sudden notching will also cause some UPS to predict as power disturbance and transfer to battery momentarily. If this happens with regularity (with every printer use) it will quickly wear out the battery.
Transient response characteristics isn't part of the specs, so the influence on the output light depends on each ballast's design.
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
That is why laser printers/copiers have been the culprit for light dimming, the toner is just plastic powder that ends up being attracted to the drum then as the page passes through the drum that powder gets deposited onto the paper and is heated up and fused to the paper. The heater will cycle when the printer/copier is in a ready mode to keep it warm enough for printing. This cycle can be as little as every 10 or 15 seconds in some cases. It was bad enough when you maybe had an incandescent light on same circuit years ago but is likely even worse with many LED lights these days. Voltage drop even in a service or feeder could possibly be exposed by this even if on different branch circuits, especially with some cheaper LED lights.