Announcement Announcement Module
Collapse
No announcement yet.
Conduit Size Page Title Module
Move Remove Collapse
X
Conversation Detail Module
Collapse
  • Filter
  • Time
  • Show
Clear All
new posts

  • Conduit Size

    I have cut some holes in my laundry room and garage walls/ceiling to run some new coaxial cable to my basement where my cable modem lives (and I can fish stuff up to my second or third floors). While I've done the damage I would like to put some conduit in so that I can later get an electrician to wire a sub-panel for my basement shop.

    My thought is that I would eventually like either 60A (cheaper) or 100A (better). Right now I have a single 15A circuit that shares outlets with all the bathrooms in the house. Eventually I would like 3 20A 220V (the thought being table saw, dust collector, and compressor) and 2 20A 120V circuits (1 for misc tools, and another for the cable modem and maybe a server). A 60A panel would probably be suitable, but at least for now I would probably want to leave the option open for 100A. The conduit would be in the ceiling above an unheated garage/basement, the ceiling/floor gap between two heated spaces, and then above my unheated basement.

    For 60A, it seems I would want to do 4 #6 THHN conductors, which would fit in 3/4" conduit. For 100A, I think I would need 4 #2 conductors, which need 1 1/4". My thought is that I should put in the 1 1/4". I wouldn't want to go any larger, because I don't want to have to drill holes any bigger than necessary.

    Also, if I do use 3/4" are there problems with using the blue flexible conduit for part of the run (up the wall and around the corner) and the gray PVC for the rest of it (the long straight part of it)?

    Thanks!

  • #2
    Re: Conduit Size

    I would put in the 1 1/4" PVC for the subpanel, and if you have room, put in a second pipe as a chase pipe for future use. Their is no problem with using ENT and then switching to PVC other than ENT can sometimes be a pain to pull thru if it is bent to tightly. If the bend is 90 degrees, I might consider using prebent PVC 90's. The smooth interior walls of the PVC allows conductors to slide thru much easier than the corrugated interior walls of ENT.

    Jeff

    Comment


    • #3
      Re: Conduit Size

      Originally posted by piette View Post
      I would put in the 1 1/4" PVC for the subpanel, and if you have room, put in a second pipe as a chase pipe for future use. Their is no problem with using ENT and then switching to PVC other than ENT can sometimes be a pain to pull thru if it is bent to tightly. If the bend is 90 degrees, I might consider using prebent PVC 90's. The smooth interior walls of the PVC allows conductors to slide thru much easier than the corrugated interior walls of ENT.

      Jeff
      Jeff,

      Thanks for the advice. My plan is to run a bunch of CATV and CAT5e now for the garage and bedrooms above it (all of the CAT5 home runs to a makeshift patch panel in the basement). I was planning on leaving an extra 3/4" conduit for more datacom. The reason I was thinking of the flex stuff is that I could avoid dealing with fittings, particularly where there is a tight corner with little room in the final joist bay (only about 3" exposed). But I didn't see 1 1/4" flex, and if it is going to be harder to pull it, I think that I should probably just go through the effort of doing PVC with fittings.

      One more question. For the PVC conduit, do I need to use cement to glue it together or is just dry fitting it OK?

      Thanks a bunch,
      Charles

      Comment


      • #4
        Re: Conduit Size

        Use the largest conduit reasonable for the datacom wiring. 3/4" can do fine but those thick Cat 5 and catv wires will fill it up really quick. Use at least 1". That wire is very delicate so you can't pull it hard if it doesn't feed smoothly. I would recommend PVC, the flexible stuff can be a bit annoying to fit through. You'll need PVC cement to join everything.

        Comment


        • #5
          Re: Conduit Size

          Originally posted by Velosapien View Post
          Use the largest conduit reasonable for the datacom wiring. 3/4" can do fine but those thick Cat 5 and catv wires will fill it up really quick. Use at least 1". That wire is very delicate so you can't pull it hard if it doesn't feed smoothly. I would recommend PVC, the flexible stuff can be a bit annoying to fit through. You'll need PVC cement to join everything.
          My plan was to leave both of the conduits empty at first, and fish the wires I am doing now so the 3/4 would be completely empty to start. I may take your suggestion though and just get 1 1/4" for both conduits, that way I can mix and match the fittings while I do it and won't have as hard a time pulling any datacom later on. I might also just leave the conduit half done, doing the straight run through the laundry room, and leaving the bit in the garage that involves turns until later. My wife will put up with a mess in the garage a second time much more than one in her laundry room. That way I can also avoid any larger holes or notches for now.

          Comment


          • #6
            Re: Conduit Size

            Definitely put in the biggest conduits you can fit. Keep in mind that you can't run data and high voltage in the same conduit. So if you are anticipating future feeds upstairs or anything like that (3 way switching, interconnected smoke detectors) you will need a pipe for that as well. The 1 1/4 for the sub panel isn't going to have a whole lot of extra room in it if you do a 100 amp sub panel.

            And yes, you will be swearing at yourself the first time you have to pull something thru those PVC pipes if you don't use glue.

            Jeff

            Comment


            • #7
              Re: Conduit Size

              Originally posted by piette View Post
              Definitely put in the biggest conduits you can fit. Keep in mind that you can't run data and high voltage in the same conduit. So if you are anticipating future feeds upstairs or anything like that (3 way switching, interconnected smoke detectors) you will need a pipe for that as well. The 1 1/4 for the sub panel isn't going to have a whole lot of extra room in it if you do a 100 amp sub panel.

              And yes, you will be swearing at yourself the first time you have to pull something thru those PVC pipes if you don't use glue.

              Jeff
              Jeff,

              There are no other hardwired smoke detectors aside from one on our third floor with bedrooms [it is on a shared circuit]. I can see how if I wanted to update the house to a set of interconnected smoke detectors I would have problems with fishing wire. Aside from the smoke detectors, can you think of anything that would need to come off the main panel? My thought is that if I have a 100A sub that I can just draw the power from their instead of from the main in the garage (which has only 4 slots left right now). Is this reasonable?

              I don't think that I can realistically run more than two of the 1 1/4 conduits without making a bunch more work, because the stud bays that I used to fish the wires have about 6 circuits going through them [oven, kitchen x2, dining room, dishwasher, family room] plus the cable television, so there isn't very much room left for drilling out the top and bottom plates without moving over a stud bay. I might end up doing that anyway just to give myself more room for the conduit, but do the loose datacom wires that I plan on running now in those existing stud/joist bays.

              Again thanks a lot, you've been really helpful.
              Charles

              Comment


              • #8
                Re: Conduit Size

                Originally posted by cpw View Post
                Jeff,

                There are no other hardwired smoke detectors aside from one on our third floor with bedrooms [it is on a shared circuit]. I can see how if I wanted to update the house to a set of interconnected smoke detectors I would have problems with fishing wire. Aside from the smoke detectors, can you think of anything that would need to come off the main panel? My thought is that if I have a 100A sub that I can just draw the power from their instead of from the main in the garage (which has only 4 slots left right now). Is this reasonable?
                I'm not so much worried about coming from the panel as much as say getting things between floors if you had to. The vast majority would come from the panel and it doesn't matter which panel for the most part. Things like smoke detectors, or three way switches for stair lighting or some kind of lighting, or a new one is whole house bath fans with interconnected timers. Things like that require you to get wires from top to bottom. If you feel you would never need anything like that, then I wouldn't get to concerned about adding a pipe for them.

                Jeff

                Comment


                • #9
                  Re: Conduit Size

                  For the 100A sub panel, why not run SER cable rated 100A. It is easy to work with and bents easily It's aluminum so it's a bit cheaper. It is used all the time for sub panels. The just run smaller conduit for low voltage stuff later on. You can't pull other wires in the service conduit anyway, so why not use te SER cable? It's round and has all 3 conductors and a ground.

                  Comment


                  • #10
                    Re: Conduit Size

                    Your code is likely different, but we are no longer allowed to use PVC pipe inside.)that's in Ontario, Canada.

                    Comment


                    • #11
                      Re: Conduit Size

                      Originally posted by QROKING View Post
                      For the 100A sub panel, why not run SER cable rated 100A. It is easy to work with and bents easily It's aluminum so it's a bit cheaper. It is used all the time for sub panels. The just run smaller conduit for low voltage stuff later on. You can't pull other wires in the service conduit anyway, so why not use te SER cable? It's round and has all 3 conductors and a ground.
                      The reason I am thinking about conduit instead of the actual wire is the cost right now. Conduit would run about $30, but for 60 feet of wire (probably with some extra just in case), I think that will be getting into the $200+ range; or at least close. I think I'll stop by the electric supply house and find out real prices so I can make a more informed decision on that.

                      Is SER something that can be run in a conduit later, or is it like Romex that it must be in free air? Do some jurisdictions frown on it inside? Would there be any problems getting it hooked into my main panel box, or would the electrician just need to get a special aluminum certified breaker?

                      Comment


                      • #12
                        Re: Conduit Size

                        Well, if you use conduit I suppose you can use aluminum wire and that would be cheaper than SE cable, but if you go with copper in the conduit,I'll bet the SER cable is cheaper. Its no problem working with SER cable. You use NO-ALOX on the connections, besides, you will only need a main lug only sub panel. Most breakers now are AL/CU approved. We use SER cable all the time fopr sub panels especially in doors. Lou

                        Comment


                        • #13
                          Re: Conduit Size

                          Originally posted by QROKING View Post
                          Well, if you use conduit I suppose you can use aluminum wire and that would be cheaper than SE cable, but if you go with copper in the conduit,I'll bet the SER cable is cheaper. Its no problem working with SER cable. You use NO-ALOX on the connections, besides, you will only need a main lug only sub panel. Most breakers now are AL/CU approved. We use SER cable all the time fopr sub panels especially in doors. Lou
                          Lou,

                          Thanks a lot. I think I'll just run SER instead of messing around with the conduit for later. The THNN wire would work out to $8 a foot later, and the 100amp SER is only about $2 a foot, and wouldn't require nearly as big holes. After seeing the 1 1/4 conduit and the SER, I am much more confident in running the wire itself (the 90" sweeps on that conduit are pretty darn large).

                          Charles

                          Comment

                          Working...
                          X