I was just about to ask about one of the junction boxes I have in my garage. See the electrician though it was a good idea to run the Romex on top of the drywall and then splice it with another wire within a surface mounted junction box. I was honestly thinking the work was crap and then considered the task of burying the box in the wall so that it wasn't exposed.
Then I read that in fact the junction boxes have to be exposed and in fact the electrician may have done perfectly to code work. Well aside from the extremely long Romex he left flopping around in the wall and the handle of Romex that he kinked into the box, and the fact he didn't ground a metal box containing wire splices. I'd very much like to get those wires back into the wall, but since the box needs to be exposed for inspection and work, is it acceptable to only have the lid of the box exposed? I know they sell blank cover plates so something like that must be done.
Also when I trim the wires to put them back into the wall, how much slack is acceptable assuming that in the future I may have to do other work? I'm thinking 6 inches of romex plus slack with unsheathed wires in the box itself.
Basically I'm cleaning up the "work" done when they installed my gas furnace in the early 80's. Basically they removed the oil furnace in the garage leaving the wire, installed the gas furnace, ran the connection wire 25 feet to the garage and punched through 2 inches of concrete and 6 inches of sill plate, spliced it to the old oil furnace connection, which then runs 25 feet to the breaker box. All I can think of is that the HVAC installer must have owned stock in a copper mine and the previous owner was deathly afraid of drywall work.