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My bedroom breaker keeps tripping even when nothing is plugged in to any of the outlet linked to this breaker. Sometimes it will keep tripping when I try to push it back up and after 10-20 min' turn back on just fine. Sometimes it won't trip for couple of days and sometimes it will trip again after 10 min'. On a regular basis here is nothing too heavy connected, just 2 power strips with phone charger and lamp, TV, and window A/C.

There are 5 outlets and one light switch on this breaker. I have replaced all the outlets to GFCI and it worked fine for few days. My thinking was, If I put the GFCI, the bad outlet will trip before the breaker. But now when it trips, when pressing on the GFCI outlet 'Reset' button, it seem like non of the outlets tripped.

What I did notice is that the wiring is 12/2 romex and the breaker is 15A. Could I be dealing with a bad breaker?! If the wiring is 12/2 should I replace the breaker to 20A?

Thank you.

  • Is the breaker a plain breaker or does it have AFCI? – manassehkatz-Reinstate Monica Jul 25 at 21:28
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    Does this breaker have a TEST button on it? – ThreePhaseEel Jul 25 at 22:37
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    You could very well have loose wires shorting out inside your wall. STOP turning the breaker back on. You could start a fire. The breaker is trying to help you. – Glenn Willen Jul 25 at 22:57
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    If a standard breaker it is tripping on a heat overload, it takes time for the breaker to cool down is probably why it keeps tripping. a window AC is not a small load and it would be better for your electronic devices to be on a different circuit, since it is intermittent are you sure there are no other outlets on the opposite side of the wall that is also drawing a load? – Ed Beal Jul 25 at 23:31
  • Are you sure the breaker is tripping with absolutely no load on the circuit? – ThreePhaseEel Jul 26 at 2:29
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You're not answering what Ed Beal and Harper are asking. Is the breaker heating up? You can check that with an infrared thermometer which you can find for somewhere south of $30.00.

You also just revealed the the breaker is an AFCI (arc fault circuit interrupter). It trips when it senses something arcing. It is quite different from a GFCI (ground fault circuit interrupter) which trips when it senses current leakage between the hot and the neutral. So they both protect the circuit but for different problems.

Lets get back to your breaker. There could be a loose conductor attached to a device or a splice, causing an arc thus tripping your breaker. Before I start to check ever device and splice. If you have another AFCI breaker in the panel, I would swap it out to see if the problem moves with the breaker. If it moves then replace the breaker. If the new AFCI trips on the same circuit then we are back to opening boxes and looking for the problem.

Good Luck.

PS Also check out Harpers comments on receptacles that are wired by stabbing into the back of a receptacle instead of installing the conductor around the side screw. He's done it many times so you won't have to look through too many of his answers to find it. By the way, I agree with him.

  • Hi Retired Master, Thanks for your detailed explanation. I didn't check for heat yet (currently don't have an infrared thermometer). I'm just trying to figure out what going on. I have described in my initial post that there are 5 power outlets on this breaker and a light switch, all in the same room. – Yos Jul 26 at 19:29
  • After the problem started I have tested the breaker per manufacturer instruction (holding the test button while pushing the breaker back on), according to manufacturer if the breaker trips immediately in that test, it's a ground fault. And is it takes 2-3 seconds to trip it's an arc fault. In my case it seem like a ground fault, That's why I have replaced all the outlets on this breaker to GFCI hopping one of the outlets will trip before the breaker. But non of the outlet tripped only the breaker. That means that either the breaker is bad?! – Yos Jul 26 at 19:29
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Window AC draws more power than a fridge and they get a dedicated circuit by code. (mostly because the loss of power to a fridge is a big inconvenience)

That said: Breakers are not peas in a pod. Some will trip below rated capacity (rare) Replacing the breaker with a 20A, given that you have 12 ga wire is a cheap and easy first kick at the cat. Take the time to verify that you have 12 ga throughout the entire circuit.

There is a cute device called a kill-o-watt. It's a box you plug into the wall, then plug your device into. It gives you the current and power actually being used. A window AC can easily draw 1500 W on it's own, a TV a couple hundred, and chargers/wall warts 5-20w each. Add lights to that.

A clip on amp meter can measure the current at the panel. Clip around the supply branch line to the breaker, and check the draw of the entire circuit. Turn various things on and off, and see what the current is.

More to the point you can see if there is a demand when nothing is on. If this is the case, then you may have an intermittent short.

A compressor (AC's have a reefer type compressor) draws substantially more power on startup. This usually is only for a few seconds.

Check also that there are no other loads on that circuit. I know of one building where the south wall on all the bedrooms was on breaker 15, the west wall on 16, the north wall on 17. The idea was that if one room got converted to an office, there would be enough power for everything.

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You have a fault in the wiring in your wall, not the breaker

Most AFCIs, including your Homeline unit, also contain a ground fault trip in order to help them catch firestarting arc-to-ground type faults (note, that the "arcs" AFCIs catch don't have to be clearance arcs through air, but can and often are creepage arcs along contaminated insulating surfaces at a damage point), and your test results are showing that that's why the breaker's tripping: it's seeing the characteristic current imbalance of a ground fault, likely caused by a wiring error or a damaged cable in the wall, and your receptacle-type GFCIs aren't being hooked up appropriately to catch that sort of thing.

It sounds like you'll have to go through the wiring on that tripping circuit, trying to see if the breaker still trips as "branches" are disconnected from the circuit's wiring topology, in order to localize this fault to the culprit wiring run, which will then have to be dealt with appropriately, either by running a new cable, or by cutting out the culprit section of cable and installing junction boxes to splice a replacement length in. Basically, this entails a "turn the breaker off, disconnect some section inside a box and cap off any loose ends, turn the breaker back on, see if it trips" loop, working systematically from the far ends of the wiring tree up towards the homerun back to the panel.

  • Thanks ThreePhase, I'll have to run another check to all outlets along with Harper's recommendation to switch from backstabbing to hook wiring. – Yos Jul 30 at 14:41
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You have an arc fault breaker. It has two jobs:

  • Detect current which is excessive
  • Detect arc faults.

Arc faults are when arcing occurs (when it's not supposed to; obviously throwing a switch is an expected arc). Arcing is the blue-white flash you may have seen when plugging in certain things to certain places. The AFCI literally listens to the power line for the distinctive sound; it sounds like hooking up speakers or plugging in a headphone, the crinkle-snap sound.

AFCIs were originally required in bedrooms to detect electric-blanket fires. Turns out, they're also fantastic at detecting backstabs.

A backstab is a method of connecting electrical wires to switches and sockets, that is used by builders in a hurry, who don't care what happens after the closing papers are signed. The connections are very hokey (what do you expect from a spring clip that you get four for 50 cents?) and they are certainly the #1 source of problems we encounter.

Most likely the fault is somewhere in the wall wiring at the sockets or switches, though possibly also in the power strip or extension cords. This is a good time to change all those sockets and switches to screw-terminal or screw-to-clamp types.

  • Thanks Harper, you are right, the outlets are back-stabbed. I'll try to hook wire the today and see if that's makes any difference. I just replaced all outlets on this breaker from screw type to new GFCI because of the same breaker tripping issue. – Yos Jul 30 at 14:36
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    If the outlets are the back-wire type where you tighten the screw to clamp, those aren't backstabs, but make sure you tighten enough. If each outlet is GFCI, then put all wires on LINE, do not use LOAD. Tripping the last GFCI should not trip any others. – Harper - Reinstate Monica Jul 30 at 15:17

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