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Can 3/4" Liquid Tight Non Metallic Flexible Conduit be run inside a PVC Sch 40 and buried 18" below ground for extra water tight for electrical wires (3 of 6awg and 1 of 10g bare copper)?

The length is about 50ft.

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  • Regardless of how hard you try, buried wires will always be considered 'wet'.
    – Jon Custer
    Oct 5, 2023 at 16:28
  • There's no "water tight" for underground wiring. You have to use wet-rated wire.
    – popham
    Oct 5, 2023 at 16:46
  • I'm beginning to think this is an XY Problem. WHY is it that you keep wanting to use LT conduit? Is there a difficult run that you don't want to try to fit rigid into? Do you think you're going to make a wet environment into a dry one by using it? Something else?
    – FreeMan
    Oct 5, 2023 at 17:15
  • because I already run the wires through the LT and it is easier for me, i did it under 1 hour. youtube.com/watch?v=pVV7kwzuxug
    – wyciwug
    Oct 5, 2023 at 17:33

2 Answers 2

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Can you?

Yes, if the PVC is big enough to get the Liquid Tight through it. (It'll need to be REALLY big to get that through there!)

The real question is:

why would you want to?

You will not be keeping your actual wires dry by doing this. You're still going to need to run UF-B (no, really, please don't do this it's a total waste of time, money & effort, but it is code legal), or individual THHN-2/THWN wires through your conduit whether you've got the Liquid Tight in there or not.

Simply bury your PVC (use the appropriate size for your wires) and pull your individual wires through and be done with it.

You'll save money. You'll save time. You'll significantly reduce your frustration level. You'll regret trying to get the Liquid Tight through there within about 3 minutes of starting, probably sooner.

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  • All exterior conduit is defined as wet. Almost all of it meets the definition. The wire insulation on appropriate wires is made to handle that...so indeed the extra conduit does nothing useful.
    – Ecnerwal
    Oct 5, 2023 at 16:49
  • Are you adding clarifying points, @Ecnerwal, or correction? I thought I basically said what you said (except for being explicit about it being a wet location), so I'm not sure which you're intending.
    – FreeMan
    Oct 5, 2023 at 17:05
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    A) AIUI, most wire is labeled both THHN-2 and THWN. B) Yes, LT can be run above ground, it's commonly used between a disconnect and outside HVAC equipment. C) Yes, you could use it in your crawl space. The question remains WHY??? AIUI, pulling wire through LT is difficult because it moves on you. Rigid conduit doesn't move and makes pulling much easier.
    – FreeMan
    Oct 5, 2023 at 17:14
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    Just reenforcing that no matter what you do, because it's wet by definition, wet-rated wiring methods are required.
    – Ecnerwal
    Oct 5, 2023 at 17:27
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    Almost any THHN you bought in the last 10 years is multi-marked as THHN-2, THWN, MTW, and a few other ratings I forget
    – Ecnerwal
    Oct 5, 2023 at 17:33
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In a nutshell, NO. The problem you'll have is making the connections into a box or panel. The non metallic connectors are large and won't allow a PVC connector to then be mounted into the box or panel.

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