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I'm adding a run of several outlets in my unfinished basement. My plan is to run most of the wires along / through floor joists and then drop a conduit in each place where I want an outlet. Since the local inspector won't allow cable in conduit, I will need to create a cable/THHN junction box at each place where I want to drop down to a wall outlet.

As illustrated below, this would require the THHN to come up from the conduit on one side of the junction box on one side and the cable to exit the side to run along the floor joist, with the junction box cover facing out of the page. However, I believe the NEC would require the junction box cover to face downward so as to remain accessible if someone were to put a ceiling in. But having the cover on the bottom would make it impossible to attach a conduit to the bottom of the box.

Any thoughts on how to resolve this? Thanks!

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3 Answers 3

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Put a bend before the box.

Use a conduit bend to bring the wires around the corner of the wall and ceiling, and move the boxes over a bit. This could be a pre-formed bend, a custom bend, or a short length of flex conduit.

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  • Hmm I love the idea of using a short length of FMC for the bend. My concern in this case is would the coupling between the EMT and FMC need to be "accessible?" I see some debate about this - some say the coupling can be concealed if it's straight; others say all couplings need to be accessible; see the link for example: forums.mikeholt.com/threads/…
    – Michael D
    Mar 6 at 21:03
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    The coupling doesn't contain wire connections. I'd have no such concerns.
    – isherwood
    Mar 7 at 13:44
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    Need a tight radius bender, or come out the top with two 90s, otherwise you'll see the bend sticking out of the ceiling. Or just do it all in EMT, that a fish tape will go down in the future. That's the concern. If you bury a whip there's a pretty good chance it'll have to be dug up to do anything. - I pull wires through FMC while it's still on the ground and w/o fittings; good luck in-situ.
    – Mazura
    Mar 7 at 22:25
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When Romex comes down a basement wall, it needs some sort of physical protection. That could be:

  • A piece of 2x4 with a slot dado'd into it
  • A piece of bent steel
  • A chunk of gas pipe
  • A three-headed dog charmed to guard the Romex

It doesn't really matter what it is, as long as it confers physical protection. Simple enough!

Here's where people make it complicated. Sometimes, they roll right past the lumber, bent steel, gas pipe and Lovecraftian pet aisles, and go into the electrical aisle and grab a piece of electrical conduit particularly. An unfortunate choice because they have confused themselves between "random piece of thing to physically protect wire" and "electrical conduit as a wiring method, with all the Chapter 3 rules which pertain to conduits as wiring methods".

Which it's not.

So I say get unconfused, get out of that aisle, and go hit the gas pipe aisle :)

I jest, but seriously, the water pipe aisle will be fine. :)

My concern in this case is would the coupling between the EMT and FMC need to be "accessible?" I see some debate about this

If we're talking "conduit as a wiring method", couplings between conduit systems can be buried if they are pullable. If you can reasonably pull wires through it.

That's what they mean by "straight". They mean the coupler/joiner of dissimilar conduit types must be straight. What you can't do is come up out of EMT, have a hard 90 plumbing elbow and then into FMC, because you wouldn't be able to pull wires through it.

NEC requires that in conduit as a wiring method, and I hope we're clear on that distinction by now, the conduit system must be consructed empty until it is complete and anchored down. Then, wires must be pulled in, using only pulling points which will remain accessible. That means every other bend in the system must be easily pulled.

Wires aren't magic and elbows aren't pullable.

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  • Re use of gas pipes, water pipes, 2x4s etc, where in the NEC does it allow that something other than metal or schedule 80 pvc conduit can be used for this purpose?
    – Michael D
    Mar 7 at 3:14
  • @MichaelD for physical protection? You could use artillery shell brasses, if the inspector is OK with it.
    – Harper - Reinstate Monica
    Mar 7 at 3:56
  • I have very little knowledge in this area, but I thought the point of electrical conduit was for physical protection. Is is not?
    – The Guy with The Hat
    Mar 8 at 2:04
  • @TheGuywithTheHat Yeah, it is strange, isn't it? Conduit as a wiring method constitutes a wireway usable for wires which lack the appropriate jacket to be used loose in walls. Such as THHN or XHHW. When used in that manner, conduit must be continuous end-to-end and built empty and the wires pulled in afterward. Some does not provide physical protection, such as ENT and sched 40 PVC.
    – Harper - Reinstate Monica
    Mar 8 at 2:24
  • Where do I get one of those three-headed dogs?
    – Mark
    Mar 8 at 4:05
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I believe the NEC would require the junction box cover to face downward so as to remain accessible if someone were to put a ceiling in.

Code doesn't deal with hypotheticals like that. If you install the junction boxes with the covers accessible now, that's fine. If somebody wants to install a ceiling later, they'll have to deal with it then.

Of course, if you think that might be you in the near future, then sure, plan for it now so you don't have to rework it then. If you don't plan to ever finish this utility space, don't worry about it.

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