GFCI with 2x 20 amp 1 pole breakers

Question

I had a 15 amp 1 pole breaker connected to a gfci in my backyard.

Now I need more juice. I decommissioned this 15 amp circuit.

I fished a 12/3 from a 2 x 20 amp 1 pole breakers thinking I was connecting a regular outlet outside as I've got 2 hot wires now.

I thought the GFCI would connect like a regular outlet until I remembered the load/line and my mistake.

Could you recommend a solution for this kind of situation. I would rather not install a double box and 2x gfci. I would like to have a single receptacle with 2x 20 amp and be able to gfci it somehow.

I could fish a new wire. Else, I ran out of idea.

It's a Nova panel 200 amp. 1985 I guess. I use Eaton cutler-hammer DNPL breakers.

The double breaker fits bottom right. Not installed on the picture yet.

Answer 1

You have the wrong breaker for what you want to do here

The Eaton DNPL (aka BRD) type of breaker is a tandem or double-stuff breaker, that has two circuit breaker mechanisms inside it that share a line terminal, but have separate load lugs. These are used extensively to "cram" circuits into a panel, as we see in your panel.

However, since both of the breakers in a double-stuff are connected to the same leg or phase of the service, you cannot use one to feed a multi-wire branch circuit (like the one you propose) without overloading the neutral, since the hot wires in a MWBC must be on different legs or phases to allow only the difference in loads to flow down the neutral, rather than the sum of the loads.

If this were a regular branch circuit, you would need to replace the bottom rightmost DNPL1515 and the empty slot with a DNPL152015, then land the wires from the old DNPL1515 on the two outer poles and the new 12AWG wires on the two inner poles. However, this creates other problems, so read on for details.

You don't have the space for a GFCI breaker

The bigger problem for what you want to do though is that you need a two pole GFCI to protect a multi-wire branch circuit, and those only come in breaker form. However, there is no such thing as a double-stuff GFCI breaker to begin with, as the electronics required to make a GFCI work take up too much space to be fit into a single breaker package along with the two breaker mechanisms.

So, you'll need to put the GFCIs somewhere else -- this could be a "spa panel" placed inline with the circuit with a 2-pole GFCI breaker in it, or a pair of GFCI receptacles or deadfronts at the "end of the line" for the MWBC in that you would have to have the two "sides" of the circuit have separate neutrals from that point on to avoid confusing the GFCIs with improperly divided neutral currents. In this situation, you'll still need to use the DNPL152015 quadplex breaker in the main panel, as described above.

Answer 2

/3 cable and double-stuff breakers, Danger danger!

You really, really need to read my treatise on double-stuff breakers.

Every single breaker in this panel is double-stuff, and the problem is you also have multi-wire branch circuits (MWBCs) - notice the red and black wires on many breakers particularly the ones in the lower left.

That slick trick you are doing, getting 2 whole circuits by running a 12/3, that is a MWBC.

Double-stuffs do not work with MWBC, at least not the way you think, because a double-stuff is not a 2-pole breaker. It is a 1-pole breaker with both hots on the same pole. Using them with MWBC you are bound to set your neutral wires on fire. You already have this problem in several places on this panel.

You must use 2-pole breakers for all your MWBCs (the alternative, handle ties, is not feasible with double-stuffs). Those are called quadplex, as discussed in my treatise linked above.

MWBC (12/3) and GFCI

An entire MWBC can be GFCI protected by one device, but it must protect the entire MWBC which means it must be a 2-pole GFCI unit. Generally those come as breakers, but you will not be using GFCI breakers in this panel!

If I had that panel, I would lay a 42 space subpanel right next to it, and abolish all those double-stuffs. MWBCs are considered obsolete because of how they interact with GFCI (not well). However I think they are fine if you have panel spaces to spare for things like 2-pole GFCI breakers, and why shouldn't you? Spaces are cheap.

Unfortunately given the sorry state of that panel, yes, your only practical choice for terminating a MWBC with GFCI is to push out to a 2-gang box and fit 2 GFCI+receptacle units side by side. You will not be using the LOAD terminals at all.

If you do use the LOAD terminals to continue the two protected circuits onward, you cannot mix their neutrals, GFCI cannot accept that. So you will not be extending onward with 12/3 but rather 12/2/2 or two 12/2‘s.

Answer 3

Try using a 2-Pole GFCI outlet, but they are harder to find.

Alternatively, depending on your set up you might be able to get away with 2 outdoor GFCI outlet or inline adapters