Dell laser printer causing periodic drops in mains voltage, flickering lights - Page 1
Forum section: electronics / general

author: nidlaX
author_rank: Frequent Contributor
timestamp: November 09, 2015, 12:29:10 pm
content: I have a Dell b1265dfw Multifunction laser printer. Early on, I noticed that when this printer enters its power-on idle state from low power standby, it would cause the lights in the room to flicker and dim for a few seconds. While idling, it will continue to cause the lights to dim and flicker for a few seconds approximately every 30 seconds or so. Flash forward to today: I was able to capture my mains voltage level over time during the lucky moments when my Mooshimeter was working. Here's what I got:As you can see, there are very regular drops in the mains voltage in that room where the laser printer is plugged in. I am wondering whether this issue is attributable to the printer's power supply, the mains supply in the room, or both? Is this acceptable behavior for a laser printer?

author: Richard Crowley
author_rank: Super Contributor
timestamp: November 09, 2015, 12:55:43 pm
content: It seems unlikely there is anything wrong with your printer. That looks like NORMAL thermostat control of the fusing roller heating element.HOWEVER, it DOES indicate flaky wiring upstream from your printer, however. The mains power should be "stiff" enough that it will show little (or NO) voltage droop when the rather modest fusing heater turns on and off. There may be a loose or corroding connection somewhere between the printer and the circuit distribution fuse/breaker panel.What does the voltage look like right where that branch circuit exits its circuit breaker? Frankly, I would be worried about the state of your mains power wiring. That kind of droop indicates that there could be a "hot spot" connection somewhere along the line which is overheating and could potentially be a source of ignition to burn your house down.

author: nidlaX
author_rank: Frequent Contributor
timestamp: November 09, 2015, 01:46:34 pm
content: Quote from: Richard Crowley on November 09, 2015, 12:55:43 pmYeah, that is the most worrisome scenario. I'll have to do some further testing to determine what exactly is going. However, could it be that there is a fault in the printer itself and the heater is drawing far more power than it is rated for?

author: Richard Crowley
author_rank: Super Contributor
timestamp: November 09, 2015, 01:51:23 pm
content: Quote from: nidlaX on November 09, 2015, 01:46:34 pmThat seems unlikely because you are not complaining that the printer seems to be running hot. Any power it draws is turned into heat. If it was drawing a lot more power, then it would be getting a lot hotter. Have you actually measured the current? Or are you only looking at the voltage droop?

author: commongrounder
author_rank: Frequent Contributor
timestamp: November 09, 2015, 03:11:21 pm
content: I bet if you plug a hair dryer into the same receptacle you are using for your laser printer (not both on at the same time), you will observe the same or more dimming of lights, only steady state. If you can get a current measurement, you can use that with the voltage drop to calculate the branch circuit resistance. A healthy branch shouldn't have more than 0.25 ohms of resistance on any wire, or 0.5 ohms total for a hot/neutral circuit. As Richard said, high resistance can be caused by a single poor splice or connection (which can concentrate power dissipation and possibly be a fire hazard). Another cause can be under-size wire over too long of a distance, as in a 100 foot run in 14-gauge where it should be 12-gauge or larger. This scenario spreads out power loss, and just wastes electrical energy in the length of wire, rather than delivering it to the device. You need to determine which problem you have, because loose/poor connection issues can cause hazards long before a conventional circuit breaker would trip.

author: IanB
author_rank: Super Contributor
timestamp: November 09, 2015, 03:32:45 pm
content: Quote from: nidlaX on November 09, 2015, 12:29:10 pmDo you live in America? I would guess so. Do you also live in an older property?This is rather common and typical with American 120 V household wiring. What happens is that there is a long run of wiring from the distribution panel to the outlet in your room where the printer is plugged in, also chained through other outlets where lights are plugged in. This wiring was designed by the installer to handle an expected current (15 A) without overheating. It was not designed to deliver 15 A to the outlet without suffering a significant voltage drop. Basically the gauge of the wire is too light to support heavy loads without sagging.You will also notice this kind of effect if you plug in a clothes iron in a bedroom. The lights will flicker bright and dim as the iron thermostat kicks in and out.The correct solution, not often seen in American homes is to have different circuits for wall sockets and for lighting. Wall sockets would sit on 20 A circuits with heavy gauge wiring, while lighting circuits would feed wall mounted lights directly and can use lighter wiring.An intermediate solution is to supply wall sockets with heavier gauge wire than code requires, but this is expensive and won't be seen unless you specify it yourself. Continuing the solution is to have more separate circuits from the panel and have fewer wall sockets on each circuit. But this also requires more wire and is more expensive. It also won't be seen unless you specify it yourself.(By the way, my laser printer makes my lights flicker too. I know from investigations it is sitting at the end of a very long daisy chained 15 A circuit.)