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    flourescent dimming

    I have LED fixtures rated 277v with a controller that uses 0-10vdc to perform dimming function.
    I have ordered dimmer switches that are rated to switch 277 vac and also have a 0-10vdc / 200ma max output for dimming.
    My concern is that the switch does not appear to meet NEC 725.121 (A) requirements thus it will require class 1 wiring methods for the 0-10v, not a problem just my peers diagree and say class 2 is exceptable.
    cooper electric sales and technical support are of no help
    Can I get some help here?

    #2
    Does it really use 0-10V or is it actually 1-10V?

    These are totally different & incompatible systems.

    0-10V is the 'theatre' way which involves a 0-10V analogue voltage passed between a lighting desk & a dimmer. This voltage is isolated & safe to touch.

    1-10V is a common standard for dimmable fluorescent ballasts but doesn't use a voltage but a current. It is intended that these terminals are connected to a variable resistor (ie. potentiometer). The lower the resistance the more current flows & the brighter the lamp. These controls tend not to be isolated from the 277 supplying the fitting & hence must be considered as being 277V above ground.

    Adrian

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      #3
      Originally posted by atomicpunk View Post
      I have LED fixtures rated 277v with a controller that uses 0-10vdc to perform dimming function.
      I have ordered dimmer switches that are rated to switch 277 vac and also have a 0-10vdc / 200ma max output for dimming.
      My concern is that the switch does not appear to meet NEC 725.121 (A) requirements thus it will require class 1 wiring methods for the 0-10v, not a problem just my peers diagree and say class 2 is exceptable.
      cooper electric sales and technical support are of no help
      Can I get some help here?
      Which dimmer switches have you ordered?
      Rob

      Moderator

      All responses based on the 2017 NEC unless otherwise noted

      Comment


        #4
        LED dimming

        I incorrectly stated flourescent dimming on my original post, but in fact I'm dimming LED fixtures.
        The switch is a Cooper wiring device Devine series part #DF10P-C10 , it is the correct switch for the dimmable LED fixtures I'm using.
        The switch delivers 0-10 vdc , 200 ma max, also switches 120/277 v
        NEC 725.121(A) (3) does not appear to cover this device. (nor informational note)
        I think this device meets standards for current limiting but is not listed class 2 or 3 compliant by code.

        Comment


          #5
          Originally posted by atomicpunk View Post
          I incorrectly stated flourescent dimming on my original post, but in fact I'm dimming LED fixtures.
          The switch is a Cooper wiring device Devine series part #DF10P-C10 , it is the correct switch for the dimmable LED fixtures I'm using.
          The switch delivers 0-10 vdc , 200 ma max, also switches 120/277 v
          NEC 725.121(A) (3) does not appear to cover this device. (nor informational note)
          I think this device meets standards for current limiting but is not listed class 2 or 3 compliant by code.
          I see nothing in the specifications that states the 0-10 volt control is class 2 or class 3 only. Are you being told otherwise?

          http://www.cooperindustries.com/cont...Pspecsheet.pdf
          Rob

          Moderator

          All responses based on the 2017 NEC unless otherwise noted

          Comment


            #6
            class 1 only

            I have consulted with other electricians, and they had wired the 0-10 v using class 2 wiring methods.I believe code does not permit class2 wiring and thus I was looking for varification.

            Comment


              #7
              Originally posted by atomicpunk View Post
              I have consulted with other electricians, and they had wired the 0-10 v using class 2 wiring methods.I believe code does not permit class2 wiring and thus I was looking for varification.
              Looking at the manufacturer's literature I see no way to wire those as class 2 or class 3.
              Rob

              Moderator

              All responses based on the 2017 NEC unless otherwise noted

              Comment


                #8
                Originally posted by infinity View Post
                Looking at the manufacturer's literature I see no way to wire those as class 2 or class 3.
                Agreed. Here is that literature. It's quite clear that the dimmer handles the full line voltage as well as providing a control voltage. You need to provide a 4 wire (neut and 3 hots) cable or two separate cables from the dimmer to the fixture which must be a class 1 wiring method. Apparently it's the violet and gray LV control that is confusing them and you. I see no way that that could be considered CL2 or 3 otherwise they would say so. Even if you could "reclassify" the wiring you would be back to a class 1 wiring method anyway.

                http://www.cooperindustries.com/cont...Pspecsheet.pdf

                -Hal
                Last edited by hbiss; 01-01-14, 07:04 PM.

                Comment


                  #9
                  Looks like they sacrificed the ability to use class 2 wiring for avoiding the requirement for a neutral in the box and working in a three-way configuration.
                  The LV control wires may be at class 2 voltage and power levels but are not listed as class 2.

                  Sent from my XT1080 using Tapatalk

                  Comment


                    #10
                    We always use Lutron where if you want a class 2 option then you need a low voltage interface module or you would wire as class 1. On page two you can see the two Lutron wiring schemes:

                    http://www.lutron.com/TechnicalDocum...ry/0301688.pdf
                    Rob

                    Moderator

                    All responses based on the 2017 NEC unless otherwise noted

                    Comment


                      #11
                      I suspected that it was not class 2 all along, my surprise is that with it being current limited to 200ma that cooper did not submit it as class2 power supply . It appears to meet the requirements of Chapter 9 table 11 (B)
                      Thanks to all

                      Comment


                        #12
                        In addition to current limiting, you need isolation between class 1 and class 2. Maybe they didn't have the space for sufficient clearances? In my last two designs, I had to use either optoisolators or transformer coupling and maintain 6.5mm spacing between any class2 and class1 components or traces on the board.
                        /mike

                        Comment


                          #13
                          Agreed. There is a lot more to making something like that CL2 compliant than just current and voltage limiting. Is it such a big deal to just use another run of 14/2?

                          -Hal

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