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Thread: Schedule 40 to Schedule 80 Transition

  1. #1
    Join Date
    Aug 2010
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    Schedule 40 to Schedule 80 Transition

    Got a question for the tradesmen out there. When you transition schedule 80 to schedule 40 pvc conduit, does the transition generally cause the wire pull through the transition to become much more difficult? I have a spec that requires schedule 80 in some areas and 40 in others and the contractor is wanting to install schedule 40 everywhere because he's saying that the transition from 40 to 80 makes the pull very difficult.

  2. #2
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    Apr 2008
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    Quote Originally Posted by mikeybmdb32 View Post
    Got a question for the tradesmen out there. When you transition schedule 80 to schedule 40 pvc conduit, does the transition generally cause the wire pull through the transition to become much more difficult? I have a spec that requires schedule 80 in some areas and 40 in others and the contractor is wanting to install schedule 40 everywhere because he's saying that the transition from 40 to 80 makes the pull very difficult.
    IMO, the transition could impact the wire pull, but not significantly as in added man power or bigger rope.

    On the project I'm on the utility spec for the underground service is a mix of sch 40 and sch 80. They are pulling the wire after I cover the pipe. The utility rarely makes things harder on themselves. Your contractor may have experience otherwise.

  3. #3
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    Quote Originally Posted by mikeybmdb32 View Post
    Got a question for the tradesmen out there. When you transition schedule 80 to schedule 40 pvc conduit, does the transition generally cause the wire pull through the transition to become much more difficult? I have a spec that requires schedule 80 in some areas and 40 in others and the contractor is wanting to install schedule 40 everywhere because he's saying that the transition from 40 to 80 makes the pull very difficult.
    Schedule 80 and Scedule 40 conduit have the same size O.D., but Schedule 80 has a smaller I.D. If using the same trade size beyond the transition, physics will obviously prevail. Beveling the I.D. edge helps... but a better remedy is to transition the smaller sizes to one size larger for SCH80. The difference isn't as prevalent for larger sizes.

    Additionally, the typical reason for using Schedule 80 is where there is increased likelihood of damage. Making these Schedule 40 instead may actually be a Code violation.
    I'll never get there. No matter where I go, I'm always here.

  4. #4
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    Pulling through PVC transistions from forty to eighty has never been a problem that I have encountered.
    If Billy Idol or John Denver is on your Ipod go and re-evaluate your life.

  5. #5
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    Jul 2003
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    We just use a reamer to taper the interior edge of the smaller i.d. Sch 80. Around here it's common to use Sch 80 up the pole on an underground service and Sch 40 the rest of the way.
    Rob

    Chief Moderator

    All responses based on the 2011 NEC unless otherwise noted

  6. #6
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    As the others have said, I don't see an issue. But you want to be sure the conduit fill calcs are besed on the Sch 80-not on the sch 40.

  7. #7
    Join Date
    Dec 2004
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    Fort Collins, CO NEC: 2011
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    I never think to ream the 80, never had a problem with it.

  8. #8
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    Dec 2007
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    Quote Originally Posted by George Stolz View Post
    I never think to ream the 80, never had a problem with it.
    It is usually a bigger problem with pushing a fish tape through than being a problem for actual conductor pulling, especially if the transition is right at an elbow, then reaming usually helps


    _______________________


    Remember to size your raceway using conductor fill for the schedule 80 in these cases.

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