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Thread: PVC 40 between outdoor receptacle & indoor cut-off switch - must it be a closed?

  1. #1
    Join Date
    Aug 2017
    Toronto, Canada

    PVC 40 between outdoor receptacle & indoor cut-off switch - must it be a closed?

    I am an electrical engineer but not a certified electrician. I know enough to ask this question so that I don't end up in a code violation bind. I've spent a good week reading forums to look for a clear answer but I don't believe I have found what I am looking for.

    The setup: I have am mounting a new outdoor electrical outlet 30" above the exit point from the house. I am using THHN-14 and not stripping ROMEX cable for the cable run. The PVC 40 pipe extends 1 to 2" into the basement headers. What I wish to do is bring those 3 cables into the house and a foot (or less) over to a cut-off switch.

    The $64000 question: must I run the PVC conduit all the way from the entry point into the house and over the electrical box of the cut-off switch? I believe this is defined as a "closed conduit circuit", by code, and hence the answer may be yes.

    The reason I would prefer not to do this is because:

    (1) It will be very tricky to create a series of connected pipes to go from the entry point to the cut-off switch box in the basement ceiling,

    (2) Thermal expansion of the PVC (if any) is a hindrance for those short length of piping in the basement (I won't easily be able to provide for thermal expansion on the short pipe),

    (3) My serious concern is that water will most likely enter that pipe in the future as the exterior PVC connections crack (due to thermal expansion in the -40C to +40C range of temperature). That water will drain directly into the electrical box.

    What I would personally like to do is have PVC conduit coming into the house for 2", and a short length of pipe going into the electrical box, but allow for 4" to 6" of exposed THHN wires between them. That would resolve all (3) issues above. I would wrap the exposed wires in electrical tape. These wires may be exposed but they are hidden above ceiling tiles. Would this be a code violation?

    If I did not know any better than I would simply had used ROMEX cable to solve this issue -- Sheathed from the basement cut-off switch box and 1" into the PVC tubing, then stripped all the way to the outdoor electrical socket. I know that some people say that this is okay but I have gone the THHN cable route due to the pipe being exposed to the sun all day.

    Thanks for the consideration of this issue and I do appreciate any follow up comments.

  2. #2
    Join Date
    Dec 2006
    Chapel Hill, NC
    I am closing this thread, in accordance with the Forum rules. This Forum is intended to assist professional electricians, inspectors, engineers, and other members of the electrical industry in the performance of their job-related tasks. However, if you are not an electrician or an electrical contractor, then we are not permitted to help you perform your own electrical installation work.

    If I have misjudged the situation, if for example this project is related to your work, then send me a Private Message. If you can show me that I am wrong, and that you are a licensed electrician (or at least a licensed apprentice), then I will reopen your post, and offer an apology for the delay and inconvenience.

    A reminder to all members, if you see a questionable post, feel free to report it by clicking the button at the bottom left corner of the post.
    They say I shot a man named Gray and took his wife to Italy
    She inherited a million bucks and when she died it came to me
    I can't help it if I'm lucky

  3. #3
    Join Date
    Feb 2003
    Bremerton, Washington
    Since I am moderator I can Washington what you are proposing would be a serious violation and the AHJ could have your power disconnected
    In Washington, for the last fiscal year ending July 30, 2017
    147,124 permits taken out
    43,401 serious violations (where the power can be ordered disconnected)
    Of those serious violations most were from property owners.
    Thats why we don't allow DIY questions.
    Last edited by tom baker; 08-06-17 at 11:28 PM.
    Moderator-Washington State
    Ancora Imparo

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