PVC vs Metallic Conduit

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  • rcampos
    Junior Member
    • Oct 2014
    • 2
    #1

    PVC vs Metallic Conduit

    Hello folks,

    This is my first solar system installation and have a question about the conduit used to run the cables from the PV array edge to my inverter. The edge of the array is on the roof about 50 feet away from the inverter and it looks like I will have to curve the conduits in several locations to get to where I want it. Does anybody know if PVC conduit is allowed for outdoor use? I leave in Michigan and the temperature varies between 0 F in winter and 98 F in the summer. I Just think it would be easier to work with PVC instead of metallic conduit...
    Thanks!
    Tags: conduit, metallic, pvc
    • inetdog
      Super Moderator
      • May 2012
      • 9909
      #2
      Originally posted by rcampos
      Hello folks,

      This is my first solar system installation and have a question about the conduit used to run the cables from the PV array edge to my inverter. The edge of the array is on the roof about 50 feet away from the inverter and it looks like I will have to curve the conduits in several locations to get to where I want it. Does anybody know if PVC conduit is allowed for outdoor use? I leave in Michigan and the temperature varies between 0 F in winter and 98 F in the summer. I Just think it would be easier to work with PVC instead of metallic conduit...
      Thanks!
      The gray PVC used for electrical work has some limited resistance to UV damage in direct sunlight, but if you are going to use it I would paint it or provide other sunlight protection.
      The linear expansion coefficient of PVC is also much greater than that of steel, so if you have a straight run of PVC between rigidly fixed endpoints and it is more than about 6 feet long, you need to look at providing expansion joints. The pipe temperature on or just above the roof can be as much as 40F higher than the air temperature away from the building.
      If you install during the summer, arrange the expansion joints so that they will not separate when the PVC cools in the winter.
      SunnyBoy 3000 US, 18 BP Solar 175B panels.

        Comment

        • Sunking
          Solar Fanatic
          • Feb 2010
          • 23301
          #3
          Originally posted by rcampos
          Does anybody know if PVC conduit is allowed for outdoor use?
          Absolutely, as long as it is LISTED RNC. Thats all the inspector wants to know. RNC is available in both Schedule 40 and 80 applications.
          MSEE, PE

            Comment

            • rcampos
              Junior Member
              • Oct 2014
              • 2
              #4
              Originally posted by Sunking
              Absolutely, as long as it is LISTED RNC. Thats all the inspector wants to know. RNC is available in both Schedule 40 and 80 applications.
              Thank you so much for the information. I think I will go for PVC as it is easier to work with. I will also take in consideration the expansion coefficient of the PVC and make sure I get the expansion joints. I'm actually planning to install it next week and it is already getting cold in Michigan

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