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Wire size based on lowest input voltage range? Multi tap devices

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    Wire size based on lowest input voltage range? Multi tap devices

    Here at work the question was brought up of what gauge primary wire should be provided for our LED drivers. The drivers are multi tap:

    120v - 277v input / 12vdc output
    1.05a @ 120v /.85a @ 208v/ .55a @ 240v / .51a @ 277v
    Operating range of 90vac - 285vac
    Max load of 1.5a @ 90vdc per driver

    The question is, when communicating to the customer what size wire to have their electrician bring to the source, should we tell them the max possible load it could draw @ 90v or the actual load based on the voltage they will be using (usually 277v)? One may require #14 where the other may require #10. What if someone rewires the drivers for 120v at a later date? Now that #14 is too small. Common sense would tell you to use the wire size required for max possible load. In this case 1.5a per driver @ 90v. Would love to know where to find the correct answer in the NEC as well.

    ​​​​​​​Thanks,

    #2
    What is the wattage of the driver?
    They say I shot a man named Gray and took his wife to Italy
    She inherited a million bucks and when she died it came to me
    I can't help it if I'm lucky

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      #3
      There is no NEC requirement to provide for possible future changes. Provision for potential future changes is solely a design decision.

      Bob

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        #4
        Originally posted by petersonra View Post
        There is no NEC requirement to provide for possible future changes. Provision for potential future changes is solely a design decision.
        And to add to that no electrician needs the manufacturer to tell them what size wire is needed. Why would you want to get involved in that?
        They say I shot a man named Gray and took his wife to Italy
        She inherited a million bucks and when she died it came to me
        I can't help it if I'm lucky

        Comment


          #5
          60w @ 12vdc or 5a on the secondary side.

          So that was my question, thank you!. We should not make the request based on potential, only what is being installed.

          Thanks for the help!

          Comment


            #6
            Originally posted by Dennis Alwon View Post

            And to add to that no electrician needs the manufacturer to tell them what size wire is needed. Why would you want to get involved in that?
            You are correct, the better way to phrase the question would have been, "Do we tell the electrician the load is 1.5a per driver based on the potential full load of driver, or the actual load based on the voltage being used.

            Sorry for the confusion.

            Comment


              #7
              It is wired per the system voltage that it is fed to. No guessing as to what MIGHT happen, the person that makes that change later is responsible for that issue at that time.

              I'm thinking you have multiple drivers on the circuit then, because at 0.51A per unit, even 14ga wire on a 15A branch can handle 23 drivers per circuit (12A ON A 15A circuit / .51A).
              __________________________________________________ ____________________________
              Many people are shocked when they discover I am not a good electrician...

              I'm in California, ergo I am still stuck on the 2014 NEC... We'll get around to the 2017 code in around 2021.

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