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We added an outdoor fireplace and trying to wire it up. I am repurposing an old generator connection on the outside of the house. Here is the current setup

10-3 wire from panel to the outside junction box. From the junction box it's solid 12 awg to the actual plug (non-GFCI). I removed the 30amp breaker in the panel and replaced with a 20amp GFCI. White neutral is connected to the panel neutral bus (verified not ground). The black wire from the 10-3 is connected to breaker. I pulled the 12 awg wire today through conduit that my landscaper left so I know it's good.

Inside the junction box I connected black/black, red/red, white/white, and green/green.

Outlet (non-GFCI) is wired black to bronze, white to silver, green to ground. No other circuit or connections are inline or connected.

Turning on the breaker everything is fine, hit the test button on the breaker and it trips like it should. Reset the breaker and walk outside and plug in my tester, 2 lights showing correct. Press the test button and circuit does not trip but plugging in even a 60 watt lamp causes this circuit to trip.

I'm not an electrician but I have done plenty of electrical work. Any help is appreciated. Literally the only break between the panel and the outlet is where the 10awg to 12awg wire connection was made.

I did test Hot/Ground @ 123v, and hot neutral at 123v. Neutral/ground tested 0.

FWIW the red hot leg on a completely separate GCFI breaker acts exactly the same way.

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  • Thanks for all the comments. I actually had a spare 20amp breaker (non-GFCI) and just wired with GFCI outlet and everything is working. I already put the panel cover back on but now I will need to pull it off to find out if those other breakers really are arc faults or now but I promise you they are all wire to a neutral bus bar. Will try and post a picture. – Chris Willis Oct 5 '20 at 12:44
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White neutral is connected to the panel neutral bus (verified not ground). The black wire from the 10-3 is connected to breaker.

Last I checked, (I don't use GFCI breakers, normally, I just put a GFCI as the first thing in line) the neutral needs to connect to the GFCI breaker neutral connection (and depending on design, you may need to connect a pigtail from the breaker to the neutral buss) otherwise the GFCI cannot possibly work.

A GFCI compares the current on the hot and neutral, and trips the GFCI function on a difference between them (5 mA nominal) - if it's not seeing the neutral return current, it will see an imbalance from the hot it does see and the neutral which it will see as 0mA if the neutral wire is not connected to it correctly.

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  • I have 8 other GCFI Circuits in the panel for things like kitchen and bathrooms. All of those breakers are wired directly to neutral bus bars and the neutral from the line is wired to the same bar. I see what you saying about hot/neutral but all my other GCFI's operate perfectly and this one is different. Just went down and checked again and everything is connected to a shared neutral bus using individual connections. – Chris Willis Oct 4 '20 at 19:10
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    @ChrisWillis -- what make and model is your electrical panel? It sounds like you have a GE panel and are confusing your AFCIs for GFCIs...in fact, can you post photos of your panel please? – ThreePhaseEel Oct 4 '20 at 19:17
  • This is the right answer, given the information provided. I don't know how your other GFCI breakers could possibly work right... possibly as ThreePhaseEel suggests they're AFCI, not GFCI, or maybe they're just malfunctioning, but you MUST hook the neutral wire to the breaker neutral for the GFCI breaker to work. There's no way to measure the current difference (and thus ground leakage) without the neutral hooked to the breaker. – Steve Sether Oct 4 '20 at 20:12
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    @ChrisWillis "I have 8 other GFCI [breakers]... All of those breakers are wired directly to neutral bus bars and the neutral from the line is wired to the same bar." No, it's not. It's really, really not. I too can confirm it is absolutely impossible for a GFCI breaker to function when wired that way. I've seen AFCIs that when installed that way will "work", albeit with degraded protection. I've also seen GE AFCIs which have a special install procedure. – Harper - Reinstate Monica Oct 5 '20 at 5:56
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You have a multi-wire branch circuit!

FWIW the red hot leg on a completely separate GCFI breaker acts exactly the same way.

This. This right here.

You have learned a trick that you can get two "circuits" out of a /3 cable if you share the neutral. The problem is, you only learned part of the story.

The full story is that the "circuits" are in fact one circuit called a Multi-Wire Branch Circuit (MWBC). This concept only works if the two sub-circuits are on opposite "poles" - i.e. 240V across them. If so, the neutral is safe; it will only handle differential current. If they're on the same pole, the neutral will be overloaded - and neutrals don't have breakers!

Further, they must have a common shut-off - one finger movement must shut off both halves of the circuit. The shut-off must use a 2-pole breaker or two breakers tied with a factory approved handle-tie - both methods also enforce the "opposite poles" rule (except on GE panels where it's possible to handle-tie breakers on the same pole - not good!)

MWBCs also have very special rules when dealing with GFCI. When either one is involved, you are forced into using the "2-pole breaker" option rather than two handle-tied breakers. No other possible breaker configuration can possibly work. No way, no how.

The only other possible way to protect MWBCs is to use a plain 2-pole breaker, then individual GFCI receptacles at each recep location. That will work, certainly.

GFCI breakers need the neutral wire. No exceptions.

10-3 cable from panel to the outside junction box. From the junction box it's solid 12 awg to the actual plug (non-GFCI). I removed the 30amp breaker in the panel and replaced with a 20amp GFCI.

White neutral is connected to the panel neutral bus (verified not ground).
The black wire from the 10-3 is connected to breaker.

Nope, will not work. GFCIs work by comparing a) current passing through on hot vs b) current passing through on neutral: They must be equal. If the neutral current doesn't go through the GFCI, then that just can't work!!! This is basic physics.

enter image description here

It has to wire like this. Or it can't work.

Turning on the breaker everything is fine, hit the test button on the breaker and it trips like it should. Reset the breaker and walk outside and plug in my tester, 2 lights showing correct. Press the test button and circuit does not trip but plugging in even a 60 watt lamp causes this circuit to trip.

Correct. That is exactly the symptom you will experience if you bypass neutral around a GFCI breaker. The GFCI tester draws too little current for the GFCI to notice the imbalance (except when you're pushing the button, obviously).

None of my other GFCI breakers are wired this way, and they work

That's literally impossible. Either they aren't wired like you think, or, they aren't GFCI breakers. AFCI is nothing like GFCI, and some AFCI breakers (notably GE's) don't need neutral to go through the breaker. So if the wiring is as you say, somebody gave you AFCI breakers. They won't cut it for GFCI protection on bathrooms or kitchens.

I pulled the 12 awg cable today through conduit that my landscaper left so I know it's good.

Remember if the cable is outside, it can't be NM-B cable (yellow). If the cable is UF-B, it is very wide and flat, and requires large conduit. (its inside diameter must be 138% of the cable's widest dimension). Generally cable in conduit is a weak choice, if you're going to do conduit you might as well use individual wires. At that point you just add another gray wire and you have 2 full circuits no MWBC.

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    Thanks for this, I will be checking the circuits. FWIW I pulled individual wires inside the conduit. I suspect you are correct on the GF vs AF but I've only been the house 4 years so those were done around the 2005 time frame. I have an electrician coming out to physically move some outlets so I will have them check the panel to make sure we are protected in those areas like the bathroom's if they are really AFCI. I made sure the breakers were on opposite poles and put a bar for single shut off. – Chris Willis Oct 5 '20 at 12:54

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