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    Control Wiring Color Code

    What is everyone commonly using for control wiring colors? Is there a color code for control wiring for 120ac 24ac and 24dc?

    I’ve seen blue and blue/white used for 24dc and red used for 120ac

    How are you guys installing control wiring?




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    #2
    Well white, grey, and green are "taken" by Code. Blue and brown are Code in Europe so that gets used a lot. Other than that anything goes. I usually use red for outputs, black for internal, and yellow for inputs on AC, and blue for DC. Makes it easy to see what goes where at a glance in panels.

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      #3
      That’s what I was hoping for, a standard color code commonly used by everyone so that you can look in a panel and see the colors and it tells you what voltage and I/O


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        #4
        Originally posted by LincHawk View Post
        That’s what I was hoping for, a standard color code commonly used by everyone so that you can look in a panel and see ...
        Terrorist bomb makers all use the same code, too. That's why we always know what wire to cut.

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          #5
          Originally posted by LincHawk View Post
          That’s what I was hoping for, a standard color code commonly used
          What's commonly used (in your area) may not actually be a standard. OTOH, UL-508 is a standard and does define a color code for certain things (check pg 26 of https://www.newark.com/wcsstore/Exte...uide-Eaton.pdf), but not everything needs to use it.

          Confusing, isn't it .

          The nice thing about standards is that you have so many to choose from.
          --Andrew S. Tanenbaum

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            #6
            NFPA 79 has a color code system for control panels. That is a "voluntary" standard, born out of the old "JIC" wiring standards. It's what most people use though.

            Green or Green / Yellow = ground conductor

            White or Grey = groundED circuit conductor (aka "neutral")

            Orange or Yellow = ungrounded circuit conductor that remains energized when the main disconnect is open (aka "foreign source")

            White with Orange or Yellow Stripes = groundED circuit conductor that goes with the above.

            Black = ungrounded line, load, and control conductors at line voltage, whatever that may be

            Red = ungrounded ac control conductors at less than line voltage, i.e. 120V (if Line is <120V) or 24VAC

            Blue = ungrounded dc control conductors

            White with Blue stripes = grounded DC control conductors

            There are lots of exceptions and acceptable alternatives, especially if identified on schematics. But even then, Green = Ground is consistent.
            __________________________________________________ ____________________________
            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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              #7
              The fact that one may often use 16 or 18 AWG is often pretty good indication it is not a power conductor. Depends on circumstances though, controls tapped off power leads changes things a bit, but often that is limited to something like an individual motor controller and not used for complex system with multiple control items.
              I live for today, I'm just a day behind.

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                #8
                Originally posted by kwired View Post
                The fact that one may often use 16 or 18 AWG is often pretty good indication it is not a power conductor. Depends on circumstances though, controls tapped off power leads changes things a bit, but often that is limited to something like an individual motor controller and not used for complex system with multiple control items.
                Yes but...a lot of industrial plants try to run #14 everywhere even on terminals too small to accept it and pushing it to motor loads on 90 C ampacity with 75 C terminals at the ends and running everything, hot, neutral, whatever the same color, whatever is on the service cart which is just one spool. Some carry both black and white at least. Don't trust 16 vs larger conductors.

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                  #9
                  Originally posted by paulengr View Post
                  Yes but...a lot of industrial plants try to run #14 everywhere even on terminals too small to accept it and pushing it to motor loads on 90 C ampacity with 75 C terminals at the ends and running everything, hot, neutral, whatever the same color, whatever is on the service cart which is just one spool. Some carry both black and white at least. Don't trust 16 vs larger conductors.

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                  That sounds more like what a place with a general maintenance man that also does electric would do to me and not what a plant with real electricians would do.
                  I live for today, I'm just a day behind.

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                    #10
                    keep in mind UL508a only covers wiring inside of control panels listed by Ul to that standard. It does not cover anything outside the scope of UL508a.

                    I would be inclined not to worry about it all that much. Use whatever colors are commonly used in the plant you are working at, but keep in mind that white and green are reserved for grounding wires and ground wires, respectively.
                    Bob

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                      #11
                      Originally posted by petersonra View Post
                      I would be inclined not to worry about it all that much. Use whatever colors are commonly used in the plant you are working at, but keep in mind that white and green are reserved for grounding wires and ground wires, respectively.
                      Wisdom there, and don't blindly assume any other place does it the same way.

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                        #12
                        Originally posted by petersonra View Post
                        . . . but keep in mind that white and green are reserved for grounding wires and ground wires, respectively.
                        Oops! White = grounded, green = grounding.
                        Master Electrician
                        Electrical Contractor
                        Richmond, VA

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                          #13
                          Originally posted by petersonra View Post
                          I would be inclined not to worry about it all that much. Use whatever colors are commonly used in the plant you are working at, but keep in mind that white and green are reserved for grounding wires and ground wires, respectively.
                          I agree with keeping with anything that is already established at a particular plant, even if it is somewhat against code.

                          I don't believe white and green reservations apply to under 48 volts?

                          HVAC low volt controls typically use both colors for other than ground(ed/ing) conductors.
                          I live for today, I'm just a day behind.

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