I'm planning a 220v circuit from a subpanel in my garage to an outdoor A/C disconnect for a mini split install. The cable would up run from the panel into the attic, across the garage along a running board, and down into the wall cavity on the appropriate wall. At some point the cable needs to exit the wall cavity into the disconnect.
But I'm unsure of what the common practice is for getting this wire from inside to outside.
Ideally, I wouldn't have to transition to conduit at all, and could just feed the cable in through a cable clamp on one of the knockouts on the back side of the A/C disconnect. However, given the box will be mounted on siding, I'm not sure how easy it will be to get the box flush enough that water intrusion isn't of at least some concern. And, even in this case, I'm not sure what the right way to go into that box is.
So maybe it would make more sense to transition from the wall cavity into flexible water tight conduit and then into the disconnect. Or maybe the solution is to run the entire circuit in conduit from panel to outside?
To try to figure out how this might be handled in a professional install, I checked out my existing A/C unit. There is a 10-2 (w/ground) UF cable which runs from my main panel in the basement, through the joists in the crawlspace, and exits the house here:
Here's the outdoors side, where it connects to the disconnect (which is right out of view at the top of the picture):
It doesn't look like whoever did this install did anything particularly special when exiting the house - there's just a hole, and although I can't see the inside end of that flex conduit, I'd bet that the cable is just "stuck in there".
In general - what's the best practice for making the transition from cable in the stud cavity to that outdoor A/C disconnect box? Should I transition into conduit somehow? Should I feed the cable into the back of the box and caulk it well? Or should I stop overthinking it and just shove the wire into some flex conduit like the people who built my house apparently did? This work will eventually have to pass an inspection as it requires a permit in my jurisdiction.