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When I installed my basement sub-panel, I installed an empty 1-1/2" conduit down about 4 feet into the crawlspace for future considerations. It just sticks about 1 foot below the floor in the crawlspace and has a temp cap on it.

The future as arrived and I plan to wire a hot tub. If I run my 6/3 NM from the panel through the conduit into the crawlspace, then just bare NB for 50' to the other side of the crawlspace and then back into another 1-1/2" conduit to the exterior LB and up to a spa GFCI disconnect:

  • do I need any sort of bushing, etc on the end of the crawlspace side of the conduit ends? I'd smooth it to remove the inner sharp edge.

  • can I seal it with putty type duct seal or do I need something else?

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    Some crawlspaces are equivalent to an unfinished basement, just not very tall. Others are little more than a fenced in packed dirt floor. If there are not already NM cables running unprotected in the crawlspace (that's your test case and you know you're OK) then the question is if there is a significantly non-zero chance of critters that could damage the cables or not. If there is then running the cable (or individual wires, which is easier) through conduit makes sense, even if code doesn't require it. But if it is a very "clean" area with no problems then your plan should basically be OK.
    – manassehkatz-Moving 2 Codidact
    Commented Dec 5 at 1:49
  • @manassehkatz-Moving2Codidact thanks. It is a fairly new home, clean, no rodent activity. The floow is packed dirt with thick vapor barrier. What about prepping the ends of the conduit (bushing, etc)...is that necessary?
    – crichavin
    Commented Dec 5 at 1:53
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    The conduit end is the part I'm not sure about. It may need a clamp, equivalent to clamping a cable going into a junction box. But I'm not sure.
    – manassehkatz-Moving 2 Codidact
    Commented Dec 5 at 1:56
  • "6/3NM" and "exterior LB up to a spa disconnect" appears to mean you intend to put NM cable in an exterior conduit, and you can't do that. It's not wet-rated.
    – Ecnerwal
    Commented Dec 5 at 2:41
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    The only "gray area" I'm aware of is if the box is in the exterior wall, so the cable technically never leaves the inside. All exterior conduit, no matter how short, is defined as wet. As for how to fix it, yes, that's the last paragraph of the answer I wrote.
    – Ecnerwal
    Commented Dec 5 at 3:10

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The correct fitting for a conduit that just ends is a conduit end-bell which provides a molded rounded edge to protect the cables leaving the conduit. We use them a lot for low voltage network cabling.

Whether your LAHJ's inspector likes that for line voltage power is better asked before the fact. A safer option (in terms of the LAHJ's inspector liking it) would be a box with a cable clamp for the cable exiting the box, or if you only intend to run a single cable in this conduit, an end fitting with a cable clamp fitted.

As for what appears to be a description of NM cable going into an exterior section of conduit, that's a hard fail on the inspection, easily avoided with a box and a transition to THWN in the conduit before it goes exterior.

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    Or I could just run conduit through the crawlspace and the THWN all the way from panel, through crawlspace to disconnect.
    – crichavin
    Commented Dec 5 at 16:28

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