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Duct into concrete building

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    Duct into concrete building

    Greetings,

    What is the typical recommended method of transitioning from underground duct bank into existing building with 12" brick wall? I am thinking the duct bank would stub up into exterior junction box with conduits going from this JB, through the wall, into the interior junction box. Both JBs would be wall mounted and at the same elevation relative to the grade.

    If anyone can recommend a good literature on this topic that covers industry practices, that would be much appreciated.

    Thanks,
    EE

    #2
    What is the reason that you're thinking of a junction box on the outside and not bringing the conduits directly through the wall?
    Rob

    Moderator

    All responses based on the 2017 NEC unless otherwise noted

    Comment


      #3
      Originally posted by infinity View Post
      What is the reason that you're thinking of a junction box on the outside and not bringing the conduits directly through the wall?
      What would be some advantages of bringing the conduits directly through the wall apart from this being a seemingly simpler install?

      Thanks,
      EE

      Comment


        #4
        Not having the box on the outside would possibly make it easier to pull in the conductors. If a box is need to transition we would probably come into the box on the inside to eliminate the need for a more expensive outdoor box.
        Rob

        Moderator

        All responses based on the 2017 NEC unless otherwise noted

        Comment


          #5
          Cut concrete floor out inside near exterior wall. Undermine foundation and stub conduits up inside of building. Encase duct bank in flowable fill/CDF/concrete to meet compaction requirements under foundation.

          Comment


            #6
            re: Cow's comment-- how deep are the conduits compared to the basement floor? Would the conduits come thru the wall or up from the floor?

            Comment


              #7
              Originally posted by PaulMmn View Post
              re: Cow's comment-- how deep are the conduits compared to the basement floor? Would the conduits come thru the wall or up from the floor?
              The top of duct bank is below the basement floor. I don't think at this point it is feasible to stub conduits up inside the building. The conduits need to come thru the wall.

              Comment


                #8
                Click image for larger version

Name:	Duct basement penetration.jpg
Views:	78
Size:	39.7 KB
ID:	2529704They are a few possibilities:

                If there is a building has an actual basement

                If the main electrical room is already located on the ground floor near the outside wall

                a lot of other possibilities.

                The problem is the wall sealing.

                There are some possibilities:

                sikaflex

                sealing silicone

                epoxy resin

                other possibilities.
                Attached Files

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