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AMD 2 - changes to conductor colour coding

AJJewsbury
It seems that AMD 2 is introducing yet another big change to colour coding - albeit only for DC systems. +ve is changing from brown to red and -ve from grey to white.


Also functional earths are changing from Cream to Pink.


Anyone know


a) why the change?

b) why the "old" (i.e. brown/blue) colours aren't permitted as an alternative?


(the 2nd question is about being able to comply with two different versions of BS 7671 at the same time - e.g. where legislation demands compliance with an older version but customer requirements are for compliance with the latest version - DC systems being increasingly common in domestic installations - e.g. PV systems.)


   - Andy.
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    AJJewsbury:

    It seems that AMD 2 is introducing yet another big change to colour coding - albeit only for DC systems. +ve is changing from brown to red and -ve from grey to white.


    Also functional earths are changing from Cream to Pink.


    Anyone know


    a) why the change?

    b) why the "old" (i.e. brown/blue) colours aren't permitted as an alternative?


    (the 2nd question is about being able to comply with two different versions of BS 7671 at the same time - e.g. where legislation demands compliance with an older version but customer requirements are for compliance with the latest version - DC systems being increasingly common in domestic installations - e.g. PV systems.)


       - Andy.


    (a) and (b) ... BS EN 60445 has already made the change. It's now harmonized. Conflicting standards have to be withdrawn.


    DC systems can have different H&S risks and it's preferable to be able to distinguish between AC and DC conductors for safety.


    Functional earth being pink already changed in BS 7671 since in Corrigendum 2018 - 2 years back, for the same reason. Combined protective and functional earth should still be identified green-and-yellow.


    Appendix 7 of the DPC has been updated with guidance on "colours to different versions" (to answer 2nd question).


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    Well as the electronics world uses red and black for DC and blithely ignores much of this standards nonsense, following the de-facto trend and using red positive is perhaps not so foolish . Pity that white purple and pink are in use as "positive" colours, while black and green are earthy and blue is negative. (actually whole looms of every wire is pink in military avionics)


    I would be very surprised if car makers and telecom systems suddenly change their colour schemes to match this, and I fully expect to still find  power over ethernet using things like orange and white and white and orange as the two poles.

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    Presumably the earthed side of a DC supply is still blue ?


    So two wire DC negative earth would be blue for earthed negative and red for positive.

    And two wire DC positive earth would be blue for the earthed positive and white for negative.

    And three wire DC would be red for positive outer, blue for earthed middle wire, and white for negative outer.


    Blue for positive "just seems wrong" even if it is the earthed side of the supply.

    Not very keen on pink for functional earth either, cream was fairy well established for the minority of installations that needed it.
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    Pink in a dim light could be taken as cream and visa versa.

    Legh
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    Legh Richardson:

    Pink in a dim light could be taken as cream and visa versa.

    Legh


    No issue there then? The previous colour for TFE in BS 7671 was Cream.


    It's important to note that Cream is not a recognized colour for conductors, the recognized colours from which single-colour and bi-colour insulation can be made are (and have been for many a long year):


    Black

    Brown

    Red

    Orange

    Yellow

    Green

    Blue

    Violet

    Grey

    White

    Turquoise

    Pink


    This list appears in item 8 of Appendix 7 (Table 7F) in the Amendment 2 DPC (although in alphabetical order of the 2-letter colour code.


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    broadgage:

    Presumably the earthed side of a DC supply is still blue ?


    So two wire DC negative earth would be blue for earthed negative and red for positive.

    And two wire DC positive earth would be blue for the earthed positive and white for negative.

    And three wire DC would be red for positive outer, blue for earthed middle wire, and white for negative outer.


    Blue for positive "just seems wrong" even if it is the earthed side of the supply.

     


    Yes, no change to Blue for mid-point (M) or neutral (N) conductors.

    Blue is only positive in negative-earth situations, and the conductor is identified as "M" not "+".

     



    Not very keen on pink for functional earth either, cream was fairy well established for the minority of installations that needed it.



    The change to pink is already in place since Corrigendum 2018 to BS 7671:2018. In reality, there is no such thing as cream for a cable colour, and hasn't been ever since the cable industry harmonized on what is in effect BS 7645 (IEC 757, implementing CENELEC HD 457 S1). (see my previous post).


    The standard to watch out for identification of cable colours is not BS 7671, but BS EN 60445: in effect, the meaning of wiring colours are stated in that standard, except the assignment of phase rotation (where required) to brown, black and grey - as some of you will be aware, some other EU countries use brown, black and black, with alphanumeric to identify phase rotation if and where needed.

     


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    mapj1:


    I would be very surprised if car makers and telecom systems suddenly change their colour schemes to match this, and I fully expect to still find  power over ethernet using things like orange and white and white and orange as the two poles.

     


    Automotive have their own standards. They refer to LV as HV these days (not sure what term is given to what we used to call the HT circuit driving the plugs).


    I'm comfy that use of the TIA 568B (or for crossover TIA 568A on one end, TIA 568B at the other) colours for CAT x infrastructure, including PoE, is covered in the relevant standards referenced from BS 7671 specifically for such purposes (BS 6701 and its intendant standards, and BS EN 50174-series and the standards referenced there).


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    That will be interesting - another change of colour for the DC in telecom type installations. Since I started with the Electricity Supply Industry, we have had: 

    red and black (red earthed positive)

    black and blue (black earthed positive) 

    blue and grey (blue earthed positive) 


    and now the proposed blue and white, with blue as the earthed positive.


    We have also recently had European kit with red and blue conductors, where red is the earthed positive. In the past, I have also had white and grey, but can’t remember which way round that was! 


    Regards,


    Alan.
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    Wiring matters article on this subject has just been published: https://electrical.theiet.org/wiring-matters/years/2020/83-november-2020/section-514-identification-and-notices-in-the-amendment-no-2-draft-for-public-comment/?utm_source=Adestra&utm_campaign=Wiring%20Matters_November%202020%20issue&utm_medium=Wiring%20Matters&utm_content=Wiring%20Matters%20e-Magazine&utm_term=3172611
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    Thanks for that summary. Rather less contentios that AFDs and earthing I suspect. 

    I think I recognise the name of that author from somewhere ?

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