My exterior outlet/garage outlets are part of a 15a tandem switch currently that's not GFCI. Looks like this:
One of the hots runs the string of outlets I want to protect, then there's a hot from the other part of the tandem switch, and a single neutral split between them. I don't think I can use a single GFCI 15A circuit and just switch the single circuit over.
Closest thing I can find is this:
But that's two pole, not one pole (and I can tell the difference in the picture, but honestly don't understand quite the difference). My panel takes QO breakers...
Any help much appreciated!
Just so people understand the context this is a new house I moved into. I didn’t ignore rules, I’m just trying to fix an issue that was there before, and do it safely. Your input is very helpful.
The top left of the panel is input to the sub-panel. The panel came with the two breakers on the left, and the breaker all the way on the right. Coming into the box were essentially three sets of wires through one metal conduit, with each set having a piece of electrical tape around them. There’s a black, red, and white bundled together, and another black red and white bundled together (14g). The two black wires go to one breaker, with the white neutral above it, and the two red wires go to the next breaker, one neutral above it. The 3rd set is a pair of black and white 12g wires that go to the 20A rightmost circuit. Then there are two circuits in the middle that have the visible square D symbol that I added. The first one on the left is the GFCI 15A circuit, not hooked up to anything but the neutral and turned off, the failed addition, and a 20A circuit hooked up to a 12g pair of black/white wires that goes out to topmost right position in the sub panel to an outdoor GFCI outlet I added (the only things I added to this panel).
Curious to know if this changes anything. Thanks for your thorough thoughts!