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Thread: Question re: wire run through concrete wall

  1. #1
    Join Date
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    Question re: wire run through concrete wall

    Quick question I haven't been able to find an answer to. I'm wiring up a new outlet from my panel to my shop, and to get there I have to go through a poured concrete wall. I'm going to run the wire through PVC in the wall and then I'd like to have it terminate at the outlet which is in a flush mount box. The panel is directly on the other side of the wall from where I want the outlet, so I'd like the conduit to terminate directly in the back of the flush mount box.

    My question is: Would this pass code? Is there a special connector to use? My plan was to just leave the PVC about 1/4" long as it exits the wall so it extends into the box.

  2. #2
    I'm talking Canadian here, but it should apply there as well. When you run the PVC conduit you have to use a TA (male threaded fitting) & a locknut to terminate in both the box and the panel. If the panel is already in place it's going to be tough to go directly into the back of it. Better to go through the wall a few inches away from the panel & use an LB fitting or another box, then from there into the side of the panel. And be sure to run a ground wire in the PVC conduit.

  3. #3
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    Ok, thanks. I figured that might be the case, but just wanted to be sure.

  4. #4
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    If you can drill a bigger hole you can glue the male fitting on a piece of pipe and shove it in from the back side into the panel. You would have to drill the hole from the inside of the panel so it lines up with a knockout. Maybe a small pilot hole then drill the big hole from the other side. Will you have an outlet you can use to power the drill if you turn off all power into that panel?
    Bill D.
    PS: My Hilti hammer drill is rated at 18" per minute in concrete with a 1/2" drill. Consider renting a hammer drill

  5. #5
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    Good thought. I do have an SDS rotary hammer, but only have bits up to 1". Will have to measure the OD of the coupling to see if it's smaller than that. Though I could probably get a core bit, it would be quite an expense for a one-off use.

    And I don't think I was explaining self well enough. I will come out the bottom of the panel (which is surface mounted) then use an L body to go into the concrete wall. When it exits the wall I'd like it to terminate immediately into the box w/ receptacle. No real benefit other than aesthetics, I guess.
    Last edited by Patrick Varley; 12-07-2018 at 11:14 PM.

  6. #6
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    In that case you just have to enlarge the hole at both ends for an inch or so, so the fitting can go down inside below flush. A star drill might be cheaper and not too hard for each end. Or drill a ring of small holes around the main hole and chisel them out. Use thnn wire, not romex, to reduce conduit size. EMT might be smaller outer diameter?
    Bil lD

  7. #7
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    Quote Originally Posted by Bill Dufour View Post
    In that case you just have to enlarge the hole at both ends for an inch or so, so the fitting can go down inside below flush. A star drill might be cheaper and not too hard for each end. Or drill a ring of small holes around the main hole and chisel them out. Use thnn wire, not romex, to reduce conduit size. EMT might be smaller outer diameter?
    Bil lD
    Would EMT running through concrete corrode over time? It does seem like EMT would have a smaller O.D.

  8. #8
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    Agree, I think the EMT is smaller. My understanding is that EMT is allowed by code through poured concrete (not embedded and not cinder block) in dry environments, however whether it actually passes may depend on regional custom or the inspector. That's why I decided to go with PVC to be safe.

  9. #9
    Quote Originally Posted by Patrick Varley View Post
    Agree, I think the EMT is smaller. My understanding is that EMT is allowed by code through poured concrete (not embedded and not cinder block) in dry environments, however whether it actually passes may depend on regional custom or the inspector. That's why I decided to go with PVC to be safe.
    Here at least, EMT is allowed in concrete that is not in contact with soil. Aluminum conduit is not allowed in concrete cause it will react badly.

  10. #10
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    Steel encased in concrete will not rust. problem is the air/concrete/steel interface.
    Bil lD

  11. #11
    Quote Originally Posted by Bill Dufour View Post
    Steel encased in concrete will not rust. problem is the air/concrete/steel interface.
    Bil lD
    Or is moisture/salt is present, as in a parkade slab. Here it's code that rebar must be epoxy coated or hot dip galvanized for those locations.

  12. #12
    Use a pvc box connector and you are good to go.

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