I have added a 6" deep bump out with a TV and an electric fireplace in the center of a wall. There is a receptacle behind the feature wall which the tv and fireplace plug into. I am also creating a removable panel to access the receptacle and coax connections. Complexity was heightened when we decided to add some puck lighting under the mantle below the tv. These are 120v hardwired pucks with a dimmer on the side of the mantle.
My plan was to tap into the receptacle and run power to the dimmer. My question is that I'm going through a couple of surfaces and not sure what the proper technique (plain romex, conduit, junction boxes, etc) I should be using to keep all this as safe as possible.
The TV and fireplace are mounted on the outside of the feature wall and their cables run inside down to the receptacle. So I only go through the feature wall surface.
The puck lights & dimmer need power from the receptacle line. So I need to have that romex attached to the receptacle inside the wall, come out of the wall, go through the front of the feature wall into the hollow center of the mantle to get to the dimmer.
I know code varies by jurisdiction, but I'm looking for some best practice advice here. Is a junction box safe with no cover? There wont actually be any wiring junctions in it, its more there just to give me a pass-through the drywall. I can have the romex come up to a junction box and simply extend to the dimmer through the front of the feature wall and into the mantle but is that ok or do I need metal conduit from the receptacle all the way to the dimmer?