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Hope someone can help. All my outlets in my kitchen work, but my two GFCI/AFCI 20A outlets occasionally and utterly randomly will flip and for the most part the AFCI light on the outlet will flash, once i reset it on the outlet its fine.

But recently now both the AFCI and the GFCI lights are flashing on the outlets at the same time, it only happens on one outlet at a time, both outlets do not flip at the same time. The main breaker at the panel never flips. If i reset the outlet its fine for days, then at some random point it will flip and start flashing again.

We dont leave any appliances plugged in, except a kettle, but this is not turned on.

The kitchen has two 20A circuits, all outlets are 20a outlets as well as the two GFCI/AFCI outlets. One for each circuit. They both go back to one 220v dual pole 20A breaker in the panel.

Could it be the breaker itself that is causing this?

Thanks

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    @FreeMan I wondered about that, but when he said it went to a 240V 20amp breaker, that's go 'ole' USA. He also called them "outlets" in his OP, another linguistic clue! Yet the bloke slipped back into the Queens English and called them "sockets" in a comment ! LOL – George Anderson Jul 2 at 15:40
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    A note of caution. If you do decide to replace the GFCI outlets, be sure to take pictures BEFORE you take the wires apart. I really believe you are dealing with a MWBC and they can get tricky to put together again if you take it all apart. Put the new outlets in exactly as the old ones. Personally I consider it unlikely both would fail in a similar manner when they are so new. – George Anderson Jul 2 at 15:44
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    MWBC circuits aren't necessarily bad. Swapping the 240 breaker with 2 120v breakers changes nothing except that you become non code compliant unless you handle tie the 2 breakers together. You'll still have a MWBC (12/3 with ground) It's the wiring method that determine it. The issue is the shared neutral. Tiny imbalances can confuse AFCI and GFCI outlets and cause them to trip. The only way to get rid of a MWBC is to run another cable for the 2nd GFCI. You can re-purpose the existing 12/3 for the first one. Not suggesting that yet, just saying. Any other of the smart guys have ideas? – George Anderson Jul 2 at 15:50
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    @LukeDollard Great, sounds like you know what you are doing. Virtually no chance the breaker is defective, but I'd check the integrity of the connections in the panel, esp the neutral. I "think" one diagnostic you could do would be to disconnect one side of the MWBC at the panel and see if that fixes the problem. It would be inconvenient because half your kitchen outlets would be dead, but it might help solve your problem. How hard would it be to run a second cable to your kitchen from the panel? – George Anderson Jul 2 at 16:45
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    @LukeDollard I do agree that your best place to start is the outlets. Check to be sure all the connections are solid, replace the "sockets" if that's what you prefer. Moisture can also contribute to tripping. You'll find it. If you don't have a digital meter to help, you'll have to take a hop in your lorry to the nearest B&Q to get a proper meter, I do hear most of the employees have their bloody heads up their arse, but what can you do! (channeling my few visits to the UK here!). Welcome to the great USA. – George Anderson Jul 2 at 17:23
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Stop throwing parts at it and actually troubleshoot

It would help to read through your GFCI/AFCI instructions and get clear on whether the device is indicating GFCI or AFCI fault. In other words, treat the indication as if it is genuine, and not just gibberish from broken junk.

Let’s ditch the red herring: it ain’t the MWBC

We know it’s not the MWBC (Multi-Wire Branch Circuit). First, there is nothing wrong with MWBCs in general, but they do require special handling for GFCI and AFCI. The idea of an MWBC is to share a neutral, and that is incompatible with two 120V sub-circuits each having independent GFCI devices. The neutrals in each GFCI’s protected zone must be kept separate from any other; and travel only with the protected partner hot.

It’s no problem to do this with MWBC wiring; the two sub-circuits simply must diverge and never share a neutral after the GFCI(s).

We know your kitchen is wired correctly because if it was wired wrong, it would instantly trip with ANY use on the shared GFCI downline, and that is not the symptom. Also it was wired by a pro, who would know better.

So it’s not an MWBC problem. MWBC is simply something you must be aware of while working on the circuit.

Whenever a GFCI trips, immediately check appliances

The first thing you must do is unplug everything on the downline of that GFCI. See if the problem clears.

Meanwhile, take those appliances to a distant unrelated GFCI and see if they trip it there. In this case you’ll also have to test for AFCI trip, so try it on an AFCI also.

Next, check the downline

Remember, we’ve already pulled all the appliances on the downline, so that’s not it. It must be in the wiring.

If that does not clear the problem, we pull the GFCI out and remove the wires on the LOAD terminals.

If you can’t abide losing power to that downline, temporarily move it to LINE. However make sure to put it back!

With LOAD terminals empty, and nothing plugged into the GFCI, it must hold and not trip. If it trips, the GFCI is defective (not likely).

Since the GFCI did not trip, we are back to troubleshooting the downline wiring. Follow it, then divide, and conquer. Reconnect it to LOAD, split what remains of the circuit and see “which side” the problem is on. Rinse wash repeat until you found it.

AFCI trouble

Since these GFCIs are also AFCI (what’s the point of that?) the AFCI will detect wiring faults in the downline, or even in the supply/upline to some point. The usual suspect is “back stab” connections at receps: convert those to side screws. Make sure the side screws are all “run down” (not sticking out, they come stuck out by default, and backstabbers ignore them because backstabbing is all about being in a hurry)... and aren’t hitting a metal box or a ground wire, e.g. as a plug is wrestled in/out.

Since AFCIs literally “listen” to the wire for the crinkle-crunch sound of electric arcing, it’s possible for them to hear that on the upline. So an AFCI trip might result in wiring problems on the LINE side of the AFCI, back to the breaker and neutral bar connections, or even a loud arc fault on another circuit!

AFCIs are not required in kitchens, and if they were, AFCI receptacles are an unacceptable shortcut unless the wiring to the panel is in metal conduit. So in all seriousness, getting rid of the AFCI function is an option.

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    I believe AFCI is required in kitchens in states that are using 2014+ NEC. Source: electricallicenserenewal.com/… – Nate S. Jul 2 at 17:31
  • Harp: good suggestions as always, but somewhere in the myriad comments, the OP said he unplugged all his appliances and the outlet trips even under those circumstances. Also, even the 2017 NEC requires AFCI protection at the main panel for nearly all 120 volt circuits including kitchen circuits. Then the kitchen outlets must also be GFCI. This is for new construction. In my jurisdiction, combination AFCI/GFCI outlets are acceptable for REMODEL work, but not new construction. Just went through all of this wiring my sons new house. – George Anderson Jul 2 at 17:35
  • We ended up going with dual function breakers in the panel so no GFCI/AFCI outlets anywhere. Means going to the panel for a trip, but my son was OK with that. – George Anderson Jul 2 at 17:36
  • @NateS. As of 2014, they did not require AFCI on circuits that required GFCI. Not 100% sure about later. – Harper - Reinstate Monica Jul 2 at 17:37
  • That whole thing has been a moving target in the last 10 years. 2020 NEC requires just about everything to be AFCI and GFCI protected, including heat pumps, electric water heaters, furnaces....just about everything. – George Anderson Jul 2 at 17:39

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