enter image description hereI have an older outdoor GFCI outlet on a dedicated circuit that trips periodically. I am planning on switching it with a regular outlet and a GFCI breaker in order to get the GFCI circuitry away from the weather. The circuit is landed on a subpanel model CH12L125B that takes Cutler Hammer/Eaton CH type breakers.

My main panel is a Siemens G3040B1200. When the subpanel was installed (3" away from the main panel), the installer brought only the hots into the subpanel and left the neutrals in the main panel. Is this OK? If I put the GFCI breaker in the subpanel I will need to find the neutral and bring it over at least (I suppose). Or should I just swap with another 15a circuit in the main panel and buy a GFCI breaker for the main panel?

I was looking for a 15a single-pole GFCI breaker for the subpanel and I was having a difficult time figuring out the current model number for the breaker I would need. I don't believe this circuit needs AFCI, self-test, or "equipment protection" (but idk). Any advice would be appreciated.

  • You are definitely going to have to pair up the neutral. But really all the neutrals should be going to the correct panels. Grounds are OK "wherever". Also surprised you have such a small subpanel. A big panel could have been put there instead with no problem and then you'd never run out of spaces. Right now it looks like you are 2 spaces away from "full again". Commented Jul 28, 2022 at 22:31
  • I know! It also would have been nice to get a panel with the same breakers as the main but it came this way unfortunately.
    – bigchief
    Commented Jul 28, 2022 at 22:36
  • 2
    Easy (and less costly) solution is an interior box (steel with exposed work cover most typically) as the first device on the circuit with a GFCI or deadfront GFCI that protects the outside circuit, (fed from its LOAD terminals) without needing to be a GFCI breaker. It can be on a nipple or offset right off the breaker box, making it as easy to find as a GFCI breaker, at (typically) less than half the cost and trivial to find.
    – Ecnerwal
    Commented Jul 28, 2022 at 22:47
  • Same brand/type may or may not have been a practical option for a bunch of reasons. Plus some electricians (like mine) have strong preferences for Eaton CH panels. Commented Jul 28, 2022 at 22:56
  • 2
    Warning, you have a bunch of alien breakers in your main panel. Many brands will appear to fit but if they’re not officially listed they may damage your bus. The Square-D Homeline breakers are right out, and the GE is probably also incompatible. There may be others but the photo is too fuzzy to read part numbers.
    – nobody
    Commented Jul 29, 2022 at 1:20

2 Answers 2


My main panel is a Siemens G3040B1200. When the subpanel was installed (3" away from the main panel), the installer brought only the hots into the subpanel and left the neutrals in the main panel. Is this OK?

No, that is not OK. This was very shabbily done and you should bring in a competent electrician to correct it, or DIY.

  • The supply breaker to the subpanel needs to be a Siemens QP250, not a GE which does not belong in this panel.
  • The Square D HOM breaker also needs to go. What is wrong with people? Replace with Siemes QP230.
  • Circuits entering the main panel that have had their hots extended into the sub, need to have their neutrals extended also. Grounds can stay where they are.

And even when you do all that stuff, you'll have panels that are completely full. No, this is not OK. You've been "living from one breaker space to the next" and look where it's gotten you.

If it were me

Look. I'm a CH super-fan. But just the same, I would tear the CH panel off the wall and throw it in the trash, and replace it with a 30-space Siemens panel. That way you can use the same breakers. 30-space because spaces are cheap, and obviously you go through breaker spaces really fast. 30 space not 30 circuits. With an accessory ground bar.

Same size as your existing panel, so all the ports will line up.

I would use a RMC metal conduit nipple for the feeder and several 3/4" metal conduit nipples linking side ports up and down the unit (just to make thru-wiring more convenient, often the wires can make it to a new breaker).

I have an older outdoor GFCI outlet on a dedicated circuit that trips periodically.

I have an older smoke detector that goes off everytime I burn toast.

The difference between my smoke detector and your GFCI is you can see smoke but you can't see ground faults, so I presume my smoke detector is doing its job, and you presume your GFCI is defective.

The GFCI is probably doing its job, and you're trying to shoot the messenger. Ground faults on outdoor wiring is really not a surprise. Try opening up all the boxes downline of the GFCI and cleaning out all the paper-wasp condominiums and fixing the water getting into the boxes.

  • 1
    It looks like your points 3-6 are already done. There are clearly ground and neutral wires going from the main to the sub, there is a dedicated ground bar, and at least the neutral bar on the right appears to be isolated from the box.
    – nobody
    Commented Jul 29, 2022 at 11:40
  • Agree with @nobody. That single #12 that enters the sub panel has its ground landed on the bar on the left of the sub panel and its neutral on a bar on the top right. That top right has a larger black w/white stripe wire attached at the top - I'd assume that's the neutral feed back to the main panel. The stranded bare ground wire (AL) seems to wend its way through the conduit to the main panel, up the left side, then has a couple of strands into a #12 screw hole in the bus bar, not a proper spot to land it. Still very worthwhile to replace the sub panel with a properly wired bigger one.
    – FreeMan
    Commented Jul 29, 2022 at 13:19
  • @nobody OK, yeah I wasn't seeing a white or green wire, and at that size (#6) the wires are required to be white and green. Ah..... I see... this is actually cable and there's like 4 inches of cable sheath on it going through the passage. Commented Jul 29, 2022 at 17:56

The part number for the breaker you're searching for is: Eaton/Cutler-Hammer CH115GFI 1 Pole Circuit Breaker. The "CH" is important. ETN makes a "BR" breaker and those will not work in your sub panel. As mentioned in the comments, there might be better ways to do this.

  • That will do it+ I like the GFCI’s close to point of use and use WR rated GFCI receptacles the electronics are encased so moisture won’t bother them.
    – Ed Beal
    Commented Jul 29, 2022 at 4:45

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