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  1. #1
    Join Date
    Apr 2007
    Posts
    74

    Hmm Routing Power on the Roof

    What is the best / leak proof way to get power to the disconnect box?

    We are installing packaged units on the roof. The units will be placed on curbs. Power will be coming up from below and passing through the roof. I assume it is best to mount the disconnect box to the side of the unit itself.

    Should we:

    (A). Make a separate penetration up through the roof, run flexible conduit to the unit and seal the roof penetration with tar.

    (B). Come up under the curb, drill a hole in the side of the curb, come out the side of the curb with a conduit adaptor, then run the conduit strait up into the disconnect box.

    (C). Come up under the curb, then go up through the packaged heat pump, and then go out the side of the heat pump directly into the disconnect box.

  2. #2
    Join Date
    Feb 2003
    Location
    Huntsville,AL
    Posts
    4,125
    none of the above --
    come thru curb with conduit to side of unit, but not touching -- Liquid- tight conduit into disconnect -- be sure to include a grounding conductor, at least #10awg --

    avoid bends at the end of a run! -- ea 90degree bend multiplies pulling tension by 2.3!
    avoid more penetrations -- maybe the one with the conduit will need to be slightly larger --
    let roofing contractor do the penetrations --
    will structure handle the extra weight?

    [I had to live with such for 45y!]
    harvest rainwater,make SHADE,R75/50/30= roof/wall/floor, use HVAC mastic,caulk all wall seams!

  3. #3
    Join Date
    Aug 2006
    Location
    Wisconsin
    Posts
    1,504
    I prefer a seperate penetration and right into the disconnect. It is much neater and less chance to leak into the unit. If it is a built up roof we put pitch pockets in and then seal our lines there. If it is a rubber roof we install witches hats and simply tighten a hose clamp around our conduit to seal. This is the way they are all installed around here. We also have to install a convenience outlet at the unit per code. That is really nice to have while servicing the unit.
    Buy American! The job you save may be your own.

  4. #4
    Join Date
    May 2004
    Location
    Frederick, MD
    Posts
    951

    as long as...

    you're running wire for the unit, don't forget to install a GFCI receptacle if there isn't one already on the roof. Or you can buy a disconnect/GFCI receptacle all in one. You just have to run the appropiate wires.

  5. #5
    Join Date
    Apr 2007
    Posts
    74

    Smile Strait Up

    My contractor says he can run the power strait up through the curb and into the bottom of the package unit then out the side of the package unit directly into the disconnect box. I think I like it that way.

  6. #6
    Join Date
    Aug 2006
    Location
    Wisconsin
    Posts
    1,504
    Quote Originally Posted by pines View Post
    My contractor says he can run the power strait up through the curb and into the bottom of the package unit then out the side of the package unit directly into the disconnect box. I think I like it that way.
    Just dont come up thru the condenser section or you will have an instant leak.
    Buy American! The job you save may be your own.

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