My Model 3 is arriving soon, and I'm in the planning stages of a DIY install of 50A service to my detached garage from the main panel in the house. Garage is currently serviced by 20A from the main panel, and there's no garage subpanel. The wire run would be about 80' between the two buildings. From house to outside: New 50A breaker goes into the 200A main panel. There's room, and I'm not even close to running 100A concurrent, much less 200. 6/3 NM-B "Romex" from breaker, through punch out at bottom of panel (via Romex connector), fished behind drywall down to near floor level. Pull the Romex into weatherproof PVC junction box attached to side of house, through some kind of PVC bushing. Underground run: Splice Romex in PVC junction box to 6 AWG THHN/THWN red, black, and white conductors. Question: what's the best way to splice here? Polaris connectors look like a good option. Exit downward from box into 80' run of 2" schedule 80 PVC from house to garage at or greater than 18" burial depth. There will be three 90 degree bends in the PVC (two vertical and one horizontal). Pull THHN conductors as well as 10 AWG THHN green for ground. Question: Can I pull the THHN green into the house behind drywall to the panel and leave the Romex ground wire unused? From underground to inside garage: PVC comes up vertically from below grade along the garage exterior wall to a right angle PVC LB conduit body for wire pulling, and entry into garage wall. Short span of 2" PVC through wall to meet another right angle LB on garage interior, oriented to exit upward. More 2" PVC running vertically up the garage drywall (surface mount) to at least 48" above floor, entering 4" metal receptacle box attached to a wall stud. Will need a threaded PVC plug to go into box with lock nut. I hope that's not too hard to find in a 2" to 3/4" reducer. NEMA 14-50 in box with 4" "exposed work" cover plate. All four THHN wires are pulled through all of this. Does all this sound right? I'd love to run the THHN all the way to the panel in the house, but conduit won't work there. So am I right in thinking that splicing THHN to Romex is the way to go here? I don't really like the idea of the exterior box, but not sure what else to do. Thanks!