I'm struggling to apply the 362 rules to metallic wireways. In this case wiremold v500. I have a job with different circumstances than usual.
Line originates from j-box in attic and enters ceiling of closet. It then goes along the back of a central SOLID square divider that separates the two doorways of the closet. It then passes through the divider into a surface mount single gang device box for toggle sw.
What NEC says: 362-9 Wireways are permitted to pass through walls if the length is unbroken.
Where I'm stuck: 1) Which Wiremold part handles the transition from the attic, through the ceiling and connects to the raceway? If it's 12/2 NM in the attic, when does it become 3 individual conductors through the raceway, i.e., where is the plastic covering removed?
2) The transition through the wall according to 362-9 must be continuous raceway through wall? If so, I'm thinking either a "Flexible Section v5700f" or two "external elbows".
My other option is to pull the mouldings and gyp-rock from the back of that central post, router a channel up to the ceiling, run the NM through and up to the attic, and cover the channel with steel plates.
Well, without looking in the Wiremold catalog for specific fittings I would run the raceway down the wall (divider) with a "mouse" at either end. A "mouse" transitions from the raceway to a NM connector and will have 1/2"KO's. Install the top one right up against the ceiling with the NM entering it from above.
At the switch box location (or rather behind) use another "mouse" with a short nipple to go through the wall into the back of a cut- in box. You would strip your jacket from the NM after the connector at the top as usual.
Keep in mind that you can use this same basic setup to sleeve the NM. Then you don't need the connector, nipple and probably not even the mice. Just pop the wiremold up through the ceiling. Slide your NM through the wiremold and through a hole in the wall into a connector on the back of your cut-in box. Behind the box use a cut off outside 90 to cover the end and the cable.
EMT would work with two connectors. No, you won't be able to run a piece of Wiremold through the wall to the box. I forgot that you are using a surface box, you will have a little more room to work with then. You would enter through a rear KO. You can also use a rigid threaded nipple and 4 locknuts if you can find one of the proper length.
I would consider just sleeving the NM though, much easier and looks better.
Wouldn't have to be clamped at the top where it enters the raceway, only where it enters the box. You don't strip the jacket off the NM inside the raceway, only as usual at the box so ther is no need to use a connector where it enters the Wiremold. The Wiremold only sleeves the NM. You can do the same thing with EMT instead of Wiremold if the appearance is not an issue.