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I'm building out a homelab and got permission from my Electrician to install a bunch of ENT "smurf tubes" everywhere for low voltage applications. Some lines running to the front of the house for possible future Fiber to the Door, and some running to low voltage wall plates for cameras or Access Points. I memorized Article 362 of the NEC and much of the other relevant chapters just to be sure I was doing it right.

I followed section 362.20 to a T, and secured it every 3 feet.

While I was out today the electrician came by and told a family member that some of installations where in violation of code. Something about how I didn't secure my conduit enough, it can't be attached to the sheathing, and has to be secured within 1 foot a junction box. Annoyingly no one wrote down what he said, no one can remember what he actually said, he isn't answering is phone and neither is his company. I tried calling the electrical inspectors office to ask them some questions but they aren't picking up either.

It's practically the weekend, so I'd like to get this fixed and learn what my code violations are if any.

Image of Conduit entering top plate of a wall in the attic The other low voltage wires are secured independently. The hole will be filled with fire blocking. Does the conduit need to be secured closer to the hole in the top plate?

Conduit curving into Structured Media Center Ignore the Coax cables, they are just temporarily placed for now. Does this conduit need to be secured closer to the Structured Media Center?

Conduit running up against a ceiling Can this conduit be secured to the cross-member of the rafter?

Conduit running up against exterior sheathing Can conduit be secured to the sheathing of an exterior wall?


I'm most interested in learning the NEC, If you could could quote me the section number of any violations I have I would be most interested. If I'm just violating a best practice and not necessarily the NEC, let me know.

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    No idea what the code rule would be in the NEC, but as far as why the rule exists, it's just common sense to never put a pipe where a nail or screw is extremely likely to be driven blind. You can add cross braces to hold the pipe out a suitable amount. I also see what appears to be yellow tape, but it doesn't remotely look like it's covering a core line coupling, so if the pipe is damaged there you should consider fixing it. Finally, core line can be a pain to fish because of the corrugation and how jiggly it is. If you strap well, the effect will be limited.
    – K H
    May 15 at 6:24
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    @KH That yellow tape is the the 362.160 marking requirement. The UL mark and warnings must be visible every 10 ft. I hadn't considered adding blocking into the wall, I'll try adding that. I've personally found the tube to be slightly easier to pull wires through, the corrugation means that only half of the surface area of the pipe is in contact with the wires at any given time.
    – freebird
    May 15 at 7:35
  • Generally if you can fish it you can pull it, and most of the challenges with core line relate to fishing it, although I'd admit blow or vacuum fishing are easier on core line. I'm actually extremely fond of it for in-slab work. Generally I find EMT or rigid ENT equally easy to pull, though I don't exceed bend limits.
    – K H
    May 15 at 8:05
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    Don't attach to the sheathing. You risk puncturing the vapor barrier. Attach to studs only or install blocking and attach to that.
    – longneck
    May 15 at 22:58
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The NEC doesn't require support within a foot of termination, but there may be some state or local amendment that may modify 362.30.

As far as attaching to sheathing I can't think of wording in the code that directly addresses that specifically, but an inspector would likely claim that the sheeting is not structurally sound for support, which would create a building code violation or not installed per UL.

Section 300.4 needs to be addressed, a couple holes and supports look like they might be closer than 1.25" to the edge of a wood penetration, you would need nail plates.

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  • Thank you, I'll get right on that. I found an old local code supplement for 300.4 that requires 2.5 inches of separation from an exterior wall when passing through a framing member, but it appears to not be present in the most recent revision. I'll need to clarify more on Monday I guess.
    – freebird
    May 15 at 22:28
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    Some follow up: the 1ft from a junction box is not a code requirement but just his best practice. Nail plates and blocking will be added where needed
    – freebird
    May 18 at 19:05
  • Not only could roofing/siding repairs be at risk of penetrating the conduit, @freebird, but the conduit clamp screws are at risk of penetrating the roofing/siding.
    – FreeMan
    May 19 at 11:58

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