I'm running some THHN wires from surface-mounted receptacles in a finished kitchen up the surface of the wall and into the attic. Surface run is wiremold 700 raceway, conduit in attic is flex. I've got the special wiremold-to-1/2 inch standard knockout fitting and plan to put a 1/2 inch male fitting on the end of the flex to attach it to the wiremold fitting. The THHN inside will be unbroken from receptacle through the wiremold and through the flex to a metal junction box in the attic.

Question: Can I just run the surface wiremold up to a hole in the ceiling that my flex male fitting is sticking out of, without installing a portal of some sort in the ceiling? The wiremold and its fitting will be secured to the wall, and the flex once through into the attic will be appropriately strapped.

Edit: To clarify, I will have an unbroken conduit run from receptacle in room to junction box in attic, although transitioning from wiremold 700 surface raceway in the room to flex through the ceiling and in the attic. Do I need to install anything special for the flex passage through the ceiling?

2 Answers 2


Your plan doesn’t make sense. AC is a cable, not conduit. It comes with wires inside already - you don’t thread wires through it.

Possibly you could physically rip the wires out but it’s not an approved conduit type to then reuse for your own wires. It’s also possible that your could buy a much longer piece of AC than you need, strip the extra, and run the exposed wires through the wiremold. But probably not, since the inner wires probably aren’t marked for that.

What you’ll probably end up having to do is put a proper junction box where the wiremold and AC meet, and join the wires with wire nuts. “Proper” meaning accessible without damaging the building, not buried in the wall.

  • Thanks - apparently I mean "flex", not AC. I will correct it.
    – Armand
    Aug 3, 2022 at 21:03

The flex will need to have the appropriate fitting to enter the box. It can't just flop into the box.

The thinnest wall conduit available is EMT. Properly installed, EMT also carries ground for you.

  • @Ecnerwal yeah fixed. Aug 3, 2022 at 22:15
  • Yes, the flex on both ends will have standard male 1/2 inch fittings with lockrings for attachment to both the metal junction box in the attic and wiremold conduit transition "box". Appreciate the suggestion of EMT; at this point I've got flex and wiremold on hand and experience using them, but will consider EMT for some longer straightish runs I'll be doing in the attic.
    – Armand
    Aug 3, 2022 at 23:37

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