I'm planning to run an electrical circuit outdoors for the first time (with permit and inspections), and I was hoping someone with more experience could tell me if my plans sound OK. For simplicity I'm going to run NM cable and sheath it in appropriately sized conduit.
Run 6" RMC nipple through sidewall of crawl space into the back of a wet locations outlet box. Cap ends with insulating bushings. Makeup connections, ground the box, and install switch plus wet locations switch cover with gasket. Run about 2' of NM liquid tight conduit from the outlet box to the device (exterior tankless water heater), using liquid tight connectors to make the connections. Makeup the connections and ground the device. Seal house penetrations and the outlet plugs for unused ports with 100% silicone.
Sounds OK? Also, a few more assumptions: no locknut is required when attaching a threaded connector to the threaded ports on the outlet box. The RMC nipple to outlet box connection should get silicone, as there is no gasket, and the silicone will not interfere with the ground bond. Are these assumptions correct?
P.S. Is RMC identical to iron pipe for water?