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I am installing an outdoor conduit that consists of four #8 AWG THHN wires inside gray 1" PVC. I need to hook it up to the main service panel and I am not sure what's the best way to do it.

I understand I can install an adapter that hooks the PVC pipe, or some other conduit, directly into a knockout in the panel. The problem is that the panel is not easily accessible without tearing down chunks of the wall on which it hangs (it's solid drywall behind the panel and stucco all around).

Or I could terminate the pipe at a conduit body near the panel, drill a 1" hole in the stucco, route the wires into the wall through the hole and somehow fish them out into the service panel through an available knockout. But then some section of the wire (maybe 6-12" long) would hang inside the wall without any conduit around it.

Is that acceptable by the code or do I need a continuous conduit all the way to the panel?

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Short answer: no it is not acceptable it needs to be continuous.

The pertinent article of the National Electrical Code follows:

300.12 Mechanical Continuity — Raceways and Cables Metal or nonmetallic raceways, cable armors, and cable sheaths shall be continuous between cabinets, boxes, fit- tings, or other enclosures or outlets.

You could terminate the conduit into a junction box and then take a cable that is approved to be fished into walls (NM or MC) from there. Then make joints in the j-box. However, the j-box has to be accessible after it is installed.

Good luck with your project!

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  • Is THHN not approved to be fished into walls? And if it's NM/MC, do I need any sort of seal/connector in place of the knockout where the cable goes into the panel? Splicing with NM in a junction box is a way to do it but it would require amending the permit (and I don't see the point of having the splice).
    – Eugene Smith
    Apr 18, 2016 at 20:13
  • THHN is not approved without a raceway. Yes, NM and MC both need a connector where they are connected to the panel. We use a short piece of tie wire or fish tape to attach the wires of the cable and pull them back into the panel then slide the locknut up the tie wire until you can secure the connector. Working in a panel is dangerous it should all be de-energized before you begin work.
    – ArchonOSX
    Apr 18, 2016 at 20:18
  • Yup, that's how you do it. Terminate in any junction box (not a conduit body), and then change wiring type for the last section, making the splice inside the junction box. They do make fittings to support NM cable entering a junction box, and you must use them.
    – Harper - Reinstate Monica
    Apr 18, 2016 at 23:20
  • I thought a conduit body is considered a type of junction box? I have another conduit (though this one is metal) terminating in a conduit body right next to the panel, installed by one of the previous owners. Is there a maximum length of NM I am allowed to have between the junction box and the panel without having to staple it to a stud?
    – Eugene Smith
    Apr 20, 2016 at 17:54
  • "Only those conduit bodies that are durably and legibly marked by the manufacturer with their volume shall be permitted to contain splices, taps, or devices." 314.16(C)(2) NM cable needs to be secured within 12 inches of a J-box or panel and every 4 ½ feet thereafter. That means even a short length should have at least one staple.
    – ArchonOSX
    Apr 20, 2016 at 20:01

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