I tried searching for an answer but couldn't come up with what I was looking for, so sorry if this has been asked before!

My wife and I recently moved into a new place which had been recently flipped. We are in a mother-in-law suite so it has definitely had some wiring added and that could be the issue if my question is not possible.

Everything worked great when we first moved in, we were there for about 4 months when we woke up one morning and the fridge was off. Reset the breaker and was off by the time we finished errands. Tried a different plug right next to it and that kept the fridge on.

The microwave is plugged into the same plug so we switched where it was plugged into (now where the fridge is) and it eventually starts popping the breaker. Whenever we needed to use the microwave I just ran an extension cord to the bathroom and left the fridge unplugged since we have an outside fridge (wanted to try and determine what the cause was, guessed the fridge was going bad at first).

Ever since I started using the bathroom plug for the microwave, my wife's hair dryer and sometimes straightener will pop the plug..

The breakers are all brand new Arc-Fault breakers, tried replacing it and that did not resolve anything.

The kitchen plugs all run on one 20 amp breaker, two plugs and one with GFCI. Nothing else runs on those plugs

The bathroom is a single plug with GFCI and is also on a 20 amp arc fault breaker, the bathroom lights also run on that breaker.

I am guessing the microwave is toasting the outlets which is causing possible arc faults? When the breaker is reset it shows the indicator for an arc fault. Currently I am trying out running the fridge on the third plug in the kitchen to see if it will stay on since the microwave has never been plugged into that. I did have the fridge plugged in to another plug in the house for an extended period and never had an issue which is why I am assuming microwave.

Is that even a possible situation?

Thanks in advanced!


Well, my experiment failed and the breaker popped.. Only after the fridge had gotten down to temp and was maintaining. The compressor went to kick on again and pop! Will be calling an electrician but advice would be helpful!

  • Item one: I'm leaning towards backstabs, loose connections, and even undersized wire. How old is the house? Any guess when the wiring was updated? Can you shut a breaker off and unscrew a suspect outlet then read the type of wire being used (written on the sheathing). Perhaps they used wrong size wire. Also, do you leave all of your lights on? Do you have candlebra lights? be sure the "only thing on the circuit turned on" is a microwave and a fridge. And the fridge is not running? Either way, it sounds like wrong wire, overheating, or bad connections overheating
    – noybman
    Feb 12, 2018 at 5:00
  • You have some combo devices which are an overcurrent circuit breaker plus GFCI or AFCI detection. Read the manual for those devices. Do they provide a way to distinguish whether the trip was caused by overcurrent, GFCI or AFCI? It matters. Feb 12, 2018 at 21:41
  • If the microwave trips the breaker do any of the lights go out? I find what today should be multiple branch circuits all on 1 breaker quite often. Microwave plus several lights or as you have found a hair dryer is usually enough to trip a 20 amp breaker, any other lights on the circuit just bring the circuit(s) that much closer to tripping.
    – Ed Beal
    Feb 14, 2018 at 16:02

4 Answers 4


It’s funny, when a safety device like an AFCI trips, people are really reluctant to consider that it might be exactly what it says on the tin.

An AFCI breaker detects arc faults - that’s where a wire is either making poor contact and normal current is causing arcing across that poor contact; or; where a wire is partially shorting with another wire (but not flowing enough current to trip the breaker).

A wide variety of wire and device problems can cause arc faults, but top of the hit-list is Backstab connections. And since your house was done hit-and-miss, and very much NOT up to Code, I bet that’s exactly what is going on here. The person used backstabs on the receptacles, and they are failing either because they are backstabs, or that + poor workmanship.

Since circuits are generally wired daisy-chain (breaker to point-of-use 1 to point-of-use 2 etc.), the core problem can be at any point in the daisy chain. When the breaker in question trips, survey which sockets lose power - they all need to be checked. Inspect where the wire attaches. Obviously you can’t inspect where a backstab attaches (and you don’t want to use them anyway), so firmly twist and pull the wire out of the backstab and look for arcing marks/spots. Then put them back on a side screw.

Lastly, if the work had been done by the seller of the house, and is substandard (and it certainly sounds substandard for reasons I’ll describe), then the seller owes you a pile of money. Because the shoddy, obviously non-permitted non-inspected work definitely should have been on the disclosure statements, and was not. I haven’t done enough real estate to know which of the various insurers covers this (title insurance???) but one of them should; they in turn will go after the seller. If none do, then you go after the seller. Shame on them!

Why it seems substandard: Code requires a bunch of dedicated circuits your house doesn’t seem to have.

  • A dedicated 20A circuit for bathroom receptacles, that serves no other loads (except if it serves 1 bathroom it can serve other loads in that bathroom).
  • Two, count em two, circuits dedicated to kitchen countertops, which can power nothing else but a gas range, a clock, or other kitchen/dining area receps.
  • Dedicated circuits for dishwasher, disposal, built in microwave, and electric range obviously.
  • There is no requirement for a dedicated circuit for a fridge, but it’s a pretty good idea. Fridges should never be on GFCI/AFCI, for the same reason fire alarms shouldn’t.
  • Dedicated circuit for laundry room.

Possible Causes for A.F.C.I. Breakers Tripping: 1.Overloaded -- electrical usage has begun to overheat circuit's wires. 2.Short Circuit -- high current resulting from a fault on the circuit. 3.Overheating Breakers -- poor contacts and/or connections at the breaker itself. 4.Arc-Fault -- sparks happening on the circuit or its outlets (lights, receptacles, switches etc.

My thought is that there might be a staple in the wiring between the plug and the breaker. The AFCI breaker is doing what it was intended to do. An electrician would be able to meg the wire to check for a failure in the insulation.


I would say they didn"t use an electrician when they built the mother in law, you need dedicated circuits to the frig,the micro and the toaster,that means only one appliance to a recpt. also the hair dryer,they all draw high amps on startup and then some.

  • were the gfci installed correctly?
    Feb 12, 2018 at 0:35
  • Not sure if it is but was checking all of my bases before I call an electrician. The microwave will pop the breaker by itself, the fridge will pop the two plugs where the microwave used to be plugged in and the dryer will pop the breaker by itself since the microwave was used on that plug. The thing that gets me is it took 4 months for this to happen, wasn't an issue when we moved in. The fridge has been plugged into the third outlet that never had the microwave and has been running for about 2 hours without failing, unlike the other two plugs.
    – Nick Inman
    Feb 12, 2018 at 0:56

My thinking is is possibly a problem at the breaker where it plugs onto the bus bar. If the electrical panel is an existing older panel say like i zinsco , this happens a lot. Also kitchens with wired with what they call a three wire circuit a lot times with the hot wire sharing a common neutral. If the two circuits are both on the same phase say , for example to a phases what you be phases sharing the same neutral a lot of heat can be created by this condition and causing the breaker to trip. Just a thought.

  • I have not seen an AFCI breaker for a zinsco panel. The op did state the AFCI breaker was in the panel. For a multi wire branch circuit 2 2 hots on the same neutral if both were on the same leg it would not trip the breaker but the neutral would be overloaded.
    – Ed Beal
    Jan 7, 2019 at 18:04
  • Yeah, I don't think Zinsco AFCIs exist. It could be FPE, if OP is in Canada or managed to import a breaker from there, but it doesn't seem especially likely.
    – Nate S.
    Jun 29, 2020 at 15:42

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