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Color Convention for Power Wires

jw0752

     I am aware of the color convention for Positive and Negative wires in electronics. Red is Positive and Black is Negative. The other day as I was hooking up a small dual supply OpAmp it dawned on me that I did not know what the color convention is for the Zero Volt Ground wire between the two supplies. Does anyone know if there is a Color Convention for this Zero wire and what that color is? Also it would be interesting to know if there are any other standardized color conventions for hookup wires such as signal or output.

 

John

  • 0

    Good question.

     

    I've tended to use Red and Black as well.

    If the voltages were mixed I often used Orange for 12v.

     

    Mains wiring tends to use Green for Earth or Ground and is a wise choice, but black is also suitable since it is being used as the negative.

     

     

     

    It may not be readily obvious to many people, but in the USA black is often used as the phase colour, while we tend to use Brown or Red.

    The latest convention is Phase can be any colour except Green or Green/Yellow.

     

    Mark

  • 0

    Red is correct for DC Positive but Black is correct for DC 0V by convention, not negative

     

    For AC mains in USA/Canada Black is LIVE, WHITE is neutral, UK and other areas Brown is Live and Blue is neutral

    LIVE

    Color wire brown.svgColor wire black.svgColor wire red.svgColor wire yellow.svg

    NEUTRAL

    Color wire blue.svgColor wire white.svg

     

    The only real consistent thing for pretty much all countries is Green, Green/Yellow or Bare copper is always GROUND

    Color wire green yellow.svgColor wire green.svgColor wire bare copper.svg

     

     

    Now depending on cores and Voltages this all can change, also older wiring may be different, to be sure check local codes and WIKI https://en.wikipedia.org/wiki/Electrical_wiring seems to also have a reasonable list but verify local codes to be sure

     

    So for DC Low voltages there is a sudo code (I doubt it is official), look to PC wiring etc for what I mean

     

    Red - 5V

    Yellow - 12V

    Black - 0V

    ....

  • 0 in reply to peteroakes

    I take the path of least resistance and follow what PSU manufacturers do:

     

    When a supply is asymmetrical, I use red for + and black for -.

    When I'm dealing with a symmetrical setup, I use the same, but the ground point in the middle is green.

    image

     

    My breadboard uses the same convention:

    image

     

     

    Of course, then there's these image :

    image

  • 0 in reply to peteroakes

    The green/yellow was to overcome people with colour bindness.

    Many people have the brown/green issue where the both look the same, and hence when brown is live and green is earth ... the result is not good.

     

     

    Mark

  • 0 in reply to Jan Cumps

    Please be careful with the assumption that GREEN is the Middle because it is not, it is ground and only ground, it is possible that 0V may be tied to GND but should not be as assumption and with alot of electronics it is undesirable , in all of the above pictures Green is GND and not 0V, the one with Black as Ground goes against ALL convention and should be regarded as wrong or atleast very missleading

     

    In the PSU picture it clearly shows that 0V can go as high as 240V above GND but no more, there will be MOVs etc to prevent it from happening but outside of that, the - and + are isolated from GND

  • 0

    Since there doesn't seem to be a hard convention for the center ground wire from a dual voltage power supply I have devised a potential candidate for your approval. My choice of colors represent that it can be either the positive or negative lead depending on the side of the power supply it is relative to. Also I have made the bread board tails blue to eliminate confusion that it is anything but the 0 reference on the bread board. Thanks for responding so quickly to my question.

     

    image

     

    John