I'm installing a subpanel that is fed by 3 #1 conductors and a #4 ground (Al, XHHW-2, individual wires). I would like to use a 2-piece clamp to secure to the subpanel and to protect the wires from the metal case. However, my understanding (possibly wrong) is that individual wires cannot be clamped. Is that true?

If that is true then how do I go about securing/protecting the wires as the enter the panel? We are still on NEC 2014.

Here is the original plan. Run individual conductors from the main panel to subpanel. The wires will be buried in 2" conduit. This 2" conduit will come out of the ground into an LB box, which will feed the wires into my workshop wall (this wall will be closed off, so the wires will be protected, so no need for conduit inside the wall, right?). The wires will then go into the panel. Do these wires need protected/clamped together as they enter the panel, or do I need to put conduit in the wall?

  • Why do you have individual wires entering your panel? These should either be in a cable, which can be clamped or in a conduit that doesn't need a clamp. – jwh20 Nov 14 '20 at 13:43

The wall isn't enough, you need a conduit there

What you're missing is that you can't have loose wires outside of a recognized Chapter 3 wiring method (i.e. cable, conduit, or some other sort of raceway), and "wires loose in a wall" isn't a wiring method that the NEC provides for. So, you need to run a short length of conduit between the LB and the panel; most often, though, you can do this with a PVC box adapter fitting instead of a short length of conduit, though, as the LB will be set up to be directly opposite a knockout on the back of the panel if you've laid out your run properly.

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    Thanks. I have some water tight flexible conduit that I can run through. I should be able to line up the LB with the subpanel, but the main panel will be a bit trickier. Can I push the flexible conduit into one of the LB ports and call it good, or do I need to use a special adapter? – tnknepp Nov 14 '20 at 23:53
  • @tnknepp -- you'd need an adapter. does the LB not line up with the panel for some reason? – ThreePhaseEel Nov 15 '20 at 1:08
  • No, not on the house side (house has brick siding). The main panel is in an interior wall and there is already a 2" hole in the brick just right for running individual wires or conduit (no idea what the hole is from). From the exterior wall I need to come in about 6', then come up about 2' to hit the panel. – tnknepp Nov 15 '20 at 11:57
  • @tnknepp -- yeah, the tricky part will be finding a way to "from-to" between a PVC LB and a flex conduit, as flex conduit connectors are designed to thread into box knockouts...you could come into a pull box with the PVC and exit with the flex? – ThreePhaseEel Nov 15 '20 at 14:53

No, you can’t clamp individual wires like that.

You shouldn’t be in a position to clamp individual wires to begin with. You should be feeding the panel with wires in conduit or cable. You shouldn’t be running individual wires unprotected.

  • Updated post with additional info. – tnknepp Nov 14 '20 at 14:21
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    Same answer. Loose wires must be in conduit, even inside walls. – nobody Nov 14 '20 at 14:28

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