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    Red-Yellow-Blue Color

    Why do modern AC units always use RED-Yellow-Blue for their phase sequencing?
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    #2
    Originally posted by mbrooke View Post
    Why do modern AC units always use RED-Yellow-Blue for their phase sequencing?
    That was the standard colour system for three phase in UK. Before the stupid ridiculous "harmonisation" came into force.

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      #3
      Originally posted by Besoeker3 View Post

      That was the standard colour system for three phase in UK. Before the stupid ridiculous "harmonisation" came into force.
      Its still common in India. I kind of like it.

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        #4
        Most rotation meters are red yellow blue or red white blue.

        Roger
        Moderator

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          #5
          Originally posted by mbrooke View Post

          Its still common in India. I kind of like it.
          I liked it too. Distinct primary colours instead of the idiotic brown, blue, grey system we now have.

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            #6
            I don't know, but they also chose red-yellow-blue for the hoses of service manifolds. (many decades ago, it was red-white-blue)
            38D864_AS01.jpg

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              #7
              Originally posted by Besoeker3 View Post
              I liked it too. Distinct primary colours instead of the idiotic brown, blue, grey system we now have.
              And a black neutral!

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                #8
                Originally posted by drcampbell View Post
                I don't know, but they also chose red-yellow-blue for the hoses of service manifolds. (many decades ago, it was red-white-blue)
                38D864_AS01.jpg
                you know, that is a really good point. Maybe thats what the HVAC engineers had in mind. I like it.

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                  #9
                  Is black used in the 24vac side of things? Maybe some 'technician' sent 480v to a thermostat and now hvac has weird colors?

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                    #10
                    Originally posted by Todd0x1 View Post
                    Is black used in the 24vac side of things?...
                    Rarely. I've seen it used as the Common on older machines, but that's pretty standardized to blue now.

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                      #11
                      Originally posted by mbrooke View Post

                      And a black neutral!
                      Yes, in my fuzzy brain, had it wrong. Phases are brown, grey and black. Neutral is blue but previously a phase colour.
                      Madness. Imagine connecting a new system to and old system.......

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                        #12
                        Originally posted by mbrooke View Post

                        And a black neutral!
                        A few years ago, I built a new office building for one of the REA utilities here. Came time to energize, so I walked out to the xfrmr to chat while they were connecting. Red, White, & Blue on the paddles. 🤦🏻‍♂️

                        Idk if the guy was new or what. But he said, “well we use red, white, and blue as phase colors” while pointing at his rotation meter.

                        Had the same thing happen on another job; lineman asked if we were ready, I gave him a thumbs up, then heard the plumber screaming.


                        Sent from my iPhone using Tapatalk
                        [COLOR="Blue"]Brought to you by Carl's Jr.[/COLOR]

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                          #13
                          Originally posted by brantmacga View Post

                          A few years ago, I built a new office building for one of the REA utilities here. Came time to energize, so I walked out to the xfrmr to chat while they were connecting. Red, White, & Blue on the paddles. 🤦🏻‍♂️

                          Idk if the guy was new or what. But he said, “well we use red, white, and blue as phase colors” while pointing at his rotation meter.

                          Had the same thing happen on another job; lineman asked if we were ready, I gave him a thumbs up, then heard the plumber screaming.


                          Sent from my iPhone using Tapatalk
                          Some utilities use Red, white, green

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                            #14
                            Originally posted by mbrooke View Post
                            Some utilities use Red, white, green
                            That must be fun.

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                              #15
                              Originally posted by zbang View Post

                              That must be fun.

                              Not much to screw up though when there is nothing NEC to worry about. (except maybe the customer service)

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