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Our house (built in 2017) has per code a large percentage of combination GFCI/AFCI breakers. We have a waffle maker that regularly trips the breaker just as its heating up cycle is about to complete. We initially got the appliance replaced by the manufacturer, but the problem continued. The symptoms apply on multiple circuits and persisted even after I replaced one of the breakers in question, so both defective breakers and wiring seem unlikely.

The breakers are Square D QO (and PON, though that shouldn't matter) 20A CAFCI breakers. The breakers have diagnostics capability, so I'm able to say confidently that the type of trip is AFCI (not GFCI or over amperage). I know there are a lot of complaints about AFCI breakers, but none of the suggested solutions have worked in my case. For example, using a surge protector doesn't seem to help.

Edit: The waffle maker is a Cuisinart WAF-F20 double waffle maker.

Edit 2: I also tried replacing all of the receptacles on this circuit, so the only thing not new in the home run to the panel.

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    It still could be the waffle maker itself. Does it have an UL/CSA label/mark on it or just a CE mark? Brand name maker would help also.
    – crip659
    Commented Dec 22, 2023 at 17:16
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    Presumably the switch (thermostat) is arcing when it opens. Which is a bit concerning for a resistive load, (should not have much inclination to overvolt when opened, unlike an inductive load) probably indicating a short life for the waffle maker, or at least its poorly designed thermostat switch. Standard designs "snap" open quickly, and to sufficient distance between contacts to limit arcing, as arcing destroys the contacts over time.
    – Ecnerwal
    Commented Dec 22, 2023 at 17:23
  • @crip659 I updated the question to include brand and model. I haven't confirmed the UL mark myself yet, but given the brand (and it's not an inexpensive one) I would be extremely surprised if it weren't.
    – jcoleman
    Commented Dec 23, 2023 at 3:05
  • @Ecnerwal I don't think it's necessarily arcing. Even a completely clean, quick switch on and off of a high load (which this would be for resistive heat) could pretty easily look like an arc to the breaker's DSP. That it happens when it's close to finished heating and is turning the heat on and off quickly and repeatedly (not when it turns on at first and stays on) adds weight to this alternative explanation.
    – jcoleman
    Commented Dec 23, 2023 at 3:05
  • Do you have any other high-draw appliances you can test there? It may not be the waffler at all. It may be the current, and the effect it has on a flawed splice. That would be literally an arc fault, which is what AFCIs are designed to detect. Commented Dec 27, 2023 at 2:50

2 Answers 2

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While doing some more troubleshooting (repeated cycles on multiple circuits to verify how consistently the problem occurred) I noticed that it worked one time on a different circuit. I noticed that that circuit happened to have a few other things plugged into it, and I figured I should eliminate that as a variable. After unplugging everything, the appliance tripped that circuit also.

Intrigued by that behavior, I plugged a 60w lamp into the original offending circuit, and voilà, the waffle maker finished its heating cycle successfully. I've subsequently repeated the experiment several times for reproducibility, and I'm now reasonably confident that the DSP algorithm used by this particular circuit breaker must treat cycling from ~0 amps as a baseline (i.e., the waffle maker cycling on/off its heating element as it seems to do frequently as it approaches the set temperature) differently from the same cycling occurring from a non-zero amps baseline circuit current.

In summary, in some cases the solution to AFCI nuisance tripping is to add a small additional load to the circuit.

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    The arc-fault breaker trips based on arcing characteristics in the circuit. The Waffle maker probably uses a switch with contacts in its thermostat. Arcing between the contacts could trip an AFCI. Adding another load is an interesting solution, I assume masking the arc (or changing the ratio of the load) (not sure how the logic in the breaker works). I have been fighting this with a washing machine and Keurig. Worth trying your idea.
    – RG Hughes
    Commented Dec 22, 2023 at 17:32
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    While this doesn't answer the "why" portion of your question (anyone have an EE degree?), it does offer an excellent workaround. +1. I'd strongly suggest that you forward this info to the manufacturer and let them know that even the replacement continued to trip the breaker and how you prevented it. It might give them a hint on designing future devices to work with finicky AFCIs.
    – FreeMan
    Commented Dec 22, 2023 at 18:55
  • Nice work. The waffle maker is a resistance heater, after all, so.. are you going to add a 60W load resistor inside the waffle maker? ;-) As alternatives you could try replacing the thermostat component inside the maker with another brand, or add an X1 capacitor from line to neutral to see whether a little filtering helps the situation.
    – Greg Hill
    Commented Dec 22, 2023 at 20:59
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    Do you have access to an oscilloscope? It might be interesting to measure what the voltage and current waveforms look like when the issue occurs.
    – ntoskrnl
    Commented Dec 23, 2023 at 18:00
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    @ntoskrnl Measuring mains with an oscilloscope is not a trivial manner.
    – Christian
    Commented Dec 23, 2023 at 20:42
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Try setting the waffle maker on the lowest setting until its ready, then try adjusting to a higher setting. I was having the same issues with my All-Clad waffle maker.

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