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how many circuits can I run in conduit?

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  • how many circuits can I run in conduit?

    thinking about doing my project differently. would like to look into using PVC non metalic conduit to pull individual wires for at least 4-5 20amp 115 volt circuits. I would like to pull a few extra for future use too. what size conduit would I need for say up to 7 12 gauge hots? I would also need a few neutrals and atleast a ground in there too.

  • #2
    Now I'm going to assume that you are running this underground since you're using pvc. You must de-rate to run this number of conductors, then you need a pull box to split things at the other end, not worth the hassles. Just run a sub -panel. If my assumption about the underground is wrong, forget the pvc and use emt unless it needs to be rigid.


    • #3
      Schedule 80 PVC
      1/2" = 6 #12 THHN
      3/4" = 12 #12 THHN
      1" = 20 #12 THHN

      Schedule 40 PVC
      1/2" = 8 #12 THHN
      3/4" = 15 #12 THHN
      1" = 25 #12 THHN

      It sounds like you're going to have more than 3 current carrying conductors in the raceway, so you have to derate the ampacity of the conductors. You have to figure out exactly what you want, then you can figure your pipe size.

      What are you feeding?
      How long is the run?
      Is it 3-phase or single phase?


      • #4
        and more ???

        what are the environmental conditions / requirements

        insulation rating

        aluminum or copper

        pvc vs. cpvc

        smurf tube


        • #5
          I want to do the run from my panel box to the second floor of an old brick home where it will be hard to fish wires up to the floor inside the walls. what I want is to add more circuits and divied up the reciptcals that are there in wire mold and add more to places that have none like the bathroom. the run of cable will be 100 ft. +/- some to where I want to mount a junction box under a covered balcony and run the lines in as needed. the cable will not be under ground but needs to be protected from weather. I don't mind using 3/4" or 1" Sch. 40 PVC conduit.

          for that nubmer of circuits how many wires do I need for ground and neutrals. I want 5 hots for use now and think it would be a good idea to have a few extra in case more are needed years later. this is just for single phase 120 volt, there are no plans to bring up any 240 volt.


          • #6
            You can't run the pvc above ground. Run in conduit. Since it's exposed to weather, run in Rigid pipe.

            You don't understand about the phase thing. Houses are single phase 220V generally. 110V is provided by splitting the 220V single phase in half with a ground.

            You will make your life much easier with a sub panel. Install a 60A 2-pole breaker in your main panel then run #6 thhn to the sub panel in the rigid conduit.

            The problem I see here is that you are trying to work with something about which you have inadequate knowledge. This can be dangerous. If you really want to do this yourself, find some books, including but not limited to the National Electrical Code.

            A common mistake/failure is in grounding and bonding. Things seem to work just fine, the job seems finished, years later a fire starts or someone gets electrocuted.

            Always remember, the individual who does the installation is always personally responsible for code violations. Not being a trade professional is no excuse. The statute of limitations starts running when the fault is discovered, not when the work is done. This means legal responsibility for your work probably lasts until after your estate is settled.


            • #7

              Why can't PVC be run aboveground? Article 352 permits it, if not exposed to physical damage. I don't think running up the side of a house would be considered subject to damage. If he was planning on running HDPE then it is not permitted (Article 353). Other than the fact that after a year of expansion and contraction the pipe is going to look like crap, I don't see a problem with it.

              I do agree with you, that this is probably a little over his head, he should have a contractor do the work.


              • #8
                Technically he can use pvc (I use it outside for lozers) BUT
       is an issue
                ....must use a heavier pvc
                ....fasteners more likely to fail
                PVC only seems easier to the inexperienced. There are issues that get overlooked, then come back to bite you in the ***. These issues are less likely to come up using rigid pipe. Other than the problem of cutting and threading to proper length, rigid is not difficult to work with.

                All that being said, this is a job for a pro. Proper connections and penetrations are critical.


                • #9

                  I run rigid everyday, it takes alot of experience to know how much to deduct for Myers hubs, Ericksons, and that piece of 3/4" that is harder to bend than any other one (always seems to come out about 5/8" longer than measured).

                  Let the pros do this project!