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How to handle momentary High Current on 120 VAC Circuit 1

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DM2

DM2

Mechanical
Oct 20, 2007
144
I have a copy/printer (Konica Bizhub C220) that I got during COVID to be able to work from the house. I needed something to print in color and scan 11 x 17 drawings.

The unit is plugged into a wall outlet. The wiring to the breaker will support 20 Amps, but the original breaker was a 15 Amp Breaker. The printer would print on the 15 Amp breaker but sometimes if the unit was asleep and turned back on, it would trip the breaker. I changed out the 15 Amp breaker for a 20 Amp breaker and it trips less often but. With COVID it's been hard to find a printer that will handle my needs or that doesn't have a 6 month delivery.

I'm trying to avoid pulling a larger wire and use a 30Amp breaker from my office to the breaker panel on the outside of my house.

Would a Start Capacitor solve the problem with the momentary loads?

Is there something else that would handle the momentary load?

Regards,
DM

"Real world Knowledge isn't dropped from a parachute in the sky but rather acquired in tiny increments from a variety of sources including panic and curiosity."
 
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If there was a 15A breaker, the 20A is probably a code violation.

I’ll see your silver lining and raise you two black clouds. - Protection Operations
 
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3DDave There are other things on the circuit (2 lighting Circuits, several outlets with nothing plugged in, and a ceiling fan). I've resorted to turning those off when I start the printer. I measured the load using a Clamp Meter and the all the circuits off...then again with the printer running...next to nothing with everything off and 14 Amps with the printer running.

Is there anything that will take the momentary load?

Others have stated that the load comes when the fuser roller warms up then it does goes down.

I did consider a 30Amp breaker and pulling large wire, but I don't think you can get a wall outlet with a rating higher than 20 Amps.

Davidbeach...no...a 20Amp breaker will protect a 12AWG wire...

Regards,
DM

"Real world Knowledge isn't dropped from a parachute in the sky but rather acquired in tiny increments from a variety of sources including panic and curiosity."
 
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See if a 20A "high magnetic" breaker is available for your panel. I know they are readily available for Square D QO panels.
 
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The problem will be the lamp inside that has a very steep positive temperature coefficient of resistance, meaning when the temperature goes down the resistance goes down, and that means it will have a very high inrush when first powered on, high enough to trip your breaker's instantaneous trip. There's not a lot you can do about it if the printer did not already have a "soft start" circuit on the power supply to the lamp.

It's possible though that it DID, but it is damaged. One cheap way to do it is with a "pre-charge" current limiting resistor that is in line with the lamp when first energized, then that resistor is shorted out with a relay after a second. Internally, if that relay contact welds or the resistor is burned out, the current limiting effect is gone and you will experience that high inrush. It might be worth having it looked at by the mfr or their service dept.

Capacitor will not help and will likely make it worse, as capacitor charging current is just like inrush too.


" We are all here on earth to help others; what on earth the others are here for I don't know." -- W. H. Auden
 
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What about a current limiting reactor in series with the load? Should be quite effective if properly sized, and has no moving parts or complicated electronics . . .

CR

"As iron sharpens iron, so one person sharpens another." [Proverbs 27:17, NIV]
 
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20A "high magnetic" breaker is the equivalent to a slow blow fuse. Both will pass a large inrush, but will still protect the wiring.
Suggestion - look up the trip curve for the breaker you have, then see if there is another that has a higher instantaneous trip rating. It is not unusual for a 20A Breaker to have a 200A or higher instantaneous trip rating. Here is some basic (possibly too much) information about tripping curves
 
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You might try a couple of different 20 A breakers. These small molded-case breakers have an enormously wide tolerance band for the magnetic trip pickup current. In general, the actual operating current of a particular breaker falls on one side or the other of this tolerance band, so you might get lucky. They aren't super expensive. If you can find a "high magnetic" breaker that fits your panelboard, it's probably worth a shot, but you may have trouble find one.
 
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You have a couple of possibilities.

1) You think you have only that printer on the circuit but in fact you have more on it then you believe.
That's a most likely problem. Put a clamp-on around the wire going to The Breaker and see what's really happening with the circuit. That printer tripping a 20A breaker is NOT reasonable at all.

I used to run a ledger laser printer, 500W gaming PC with a huge 80lb CRT monitor, all my network appliances including a DSL modem that heated the middle of my house up and the ancient clapped-out 15A breaker feeding it all and other things NEVER tripped once.

2) The power supply in it is buggered. It has an inrush limiter that could be blown. The supply sure doesn't look like it could pull 20A.

You could get a 1500W UPS and put the unit on it.

I had a hydraulic lift table way out in a plant sharing the circuit with a PC. Every time the lift table got commanded up it reset the computer. I finally put a UPS on the computer and every single time someone upped the table the UPS beeped and took over for about 1 second. This went on for YEARS.

You could get a LARGE gauge extension cord and use a completely unrelated outlet and see what happens.

Keith Cress
kcress -
 
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I've read a number of recommendations not to connect a Laser printer to a UPS (CyberPower - Can I connect My UPS to a Laser Printer as it can damage the UPS.

itsmoked - I did connect a clamp meter to the circuit at the breaker which is how I determined the load with and without the printer connected.

I have a data logging Fluke Meter that can log the current draw and plot the curve, but haven't tried it yet. Not sure if the frequency of the meter will capture the inrush current and will need to give it a try.

I downloaded the Square D catalog for my breaker panel sometime ago. Sure enough there is a High Magnetic circuit breaker listed as a Model QO115HM (15 Amp) and Q0120HM (20 Amp). Unfortunately no body has these in stock. Further the existing breaker is a GFCI because of an electrical outlet on my front porch. This will mean i'm going to have to change the outlet on my front porch to a GFCI right?

Just out of curiosity, why wouldn't a start capacitor work?

Regards,
DM

"Real world Knowledge isn't dropped from a parachute in the sky but rather acquired in tiny increments from a variety of sources including panic and curiosity."
 
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A GFI breaker... Well that's the entire problem!! Why do I never think of asking about these pests on issues like this? It's a good thing you mentioned it.

You need to ditch that stupid thing immediately. It's not liking the waveform coming out of your printer.

I have a lame little house-burner plastic floor heater in my bathroom. Just turning ON that heater to low would trip my cantankerous GFI every other time. I changed out the GFI for another and that fixed it.

In your case that likely won't fix it because you've already switched breakers. You simply cannot use one with that printer.

Find a non-GFI somewhere including in your panel. Try switching it with another circuit breaker in the panel. Pick a "simple" circuit that has a few bedroom lights or something. Skip any that have big switching power supplies like a flatscreen TV or a gaming computer.

When your printer powers-up it causes a ground bounce that exceeds a mere 5mA and TRIP! It wouldn't matter if you used a 50A breaker it's the GFI tripping, it's not an "overload".

Are you absolutely sure Home Despot doesn't have 3 different brand breakers that would work in your panel?? Take out the breaker or better yet a non-GFI breaker out of your panel. Go to HD with it and find the 15A, single pole breakers and physically compare the busbar-pinch, the length, and specifically the precise configuration of how the breaker hooks into the sheetmetal on the end the wire screws into. If those match it'll work. You do NOT need a High Magnetic in this case as the problem is NOT inrush it's the GFI.

Also pick up a GFI outlet to go into your GFI application receptacle. ONLY BUY NAME BRAND like Hubbel or Leviton. Use this to guard life on the porch and not the entire cicuit.

A capacitor can not work nor would you ever want that grenade sitting somewhere to detonate eventually. It can't work because with AC you cannot bulk store energy like with DC. A cap would charge and discharge 120 times a second while not providing "stored energy" to support some, in this case, imagined excess inrush.


Keith Cress
kcress -
 
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Itsmoked...thanks for your response...
I searched Home Depot and the website says there are none in my locations. I could go to the company we buy our electrical stuff from, but I ended up ordering it on Amazon and it will be here on Tuesday.

In terms of Name Brand GFIC's, I would agree. When I buy stuff and Lowe's or Home Depot, it's difficult to find the spect's on the product on their site, so I end up Googling the brand and part number to see what's available on the OEM's web site.

I had considered getting standard 20 Amp breaker (without the GFCI) to try and see it the printer kept causing the breaker to trip but since i'm getting the write breaker in a day or so, i'm just going to get a GFCI outlet and replace the one on my front porch and plug in the new breaker...

Regards,
DM

"Real world Knowledge isn't dropped from a parachute in the sky but rather acquired in tiny increments from a variety of sources including panic and curiosity."
 
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Outdoor receptacles (including GFCI receptacles) now need to be rated "weather resistant" and marked WR. Tamper resistance is also a good idea even if it's not code required.
 
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DM2 said:
Just out of curiosity, why wouldn't a start capacitor work?
Click to expand...

A "starting capacitor" is used in single phase AC induction motors in order to create a virtual "phase shift" to start the motor turning since single phase provides no relative rotation. But when a motor or machine gets old and starts to wear out, so-called "hard start kits" are sold to add more capacitance to an existing single phase motor circuit in an attempt to better utilize the available energy in the circuit by temporarily improving the power factor of the motor start windings so that more of that energy is creating torque instead of VARs.

Bottom line for you though, a "start capacitor" would have nothing to do with anything that is not a single phase induction motor issue. The power factor of a resistance heating load, which is the issue here, it already 1.0, so adding a capacitor would actually make things worse (by having to charge the capacitor), not better.


" We are all here on earth to help others; what on earth the others are here for I don't know." -- W. H. Auden
 
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sorry for the late reply...These days when you order something on Amazon, you tend to think it will be here in a day or so. I ordered the breaker and it took 3 weeks to get to me. I could have gotten it from our companies electric supplier, but they wanted $30+ dollars and Amazon was $13.

In any case I just replaced it this morning and it's working as expected. I've kept the lights on that i'd normally have to turn off and waited until the printer was idle for several hours (this is typically when the fuser roller heeds to be heated up). Works like a champ.

Only noticeable issue is that the lights in this room (home office) still flicker when the printer starts up and for several minutes after it prints... The bulbs are incandescent and it only happens to bulbs on the same breaker. I've verified that the bulbs are screwed in the socket and next will be to have a look at the light switch...Oddly enough this room has 3 switches a) for the lights, b) for the fan built into the light, c) unknown...possible an outlet but haven't really checked. I did replace the light switch several years ago with an illuminated switch (did that thru out the house cause i'm tired of feeling around in the dark for the switch.

Regards,
DM

"Real world Knowledge isn't dropped from a parachute in the sky but rather acquired in tiny increments from a variety of sources including panic and curiosity."
 
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It's no surprise that the lights on the same circuit flicker, your printer inrush current will cause a local voltage drop.
 
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