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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.
  • 0
    gkenyon:
    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.




    Thanks Graham. Thinking about it, I can still come up with a DC installation that satisfies BS 7671:2018 and AMD2 simultaneously if I ignore the colour codes and mark everything L+/L- etc.


    Any idea why green is still conspicuous by its absence from table 51 for line conductors of ELV and control circuits? (514.4.5 removed its objection to green quite a while ago now).


       - Andy.


  • 0
    Yes, alphanumeric is definitely an option.


    Regards Green, an ELV circuit may well be a power circuit, in which case 514.4.5 still precludes the use of green. If the conductor is only supplying wetting current, then I think Table 51 doesn't apply.


    However, does a control circuit strictly have a "line" conductor (except for a common power line perhaps)?


    Certainly, 514.4.5 in its current form recognises that it's not possible to prohibit green from being used for common scenarios such as:

     - Structured cabling, datacomms, and telephony using the plethora of multi-pair cables that use green cores (in fact, standards called out by the standards referred to in BS 7671 require the colour green, so that would indeed be nonsensical).

     - Detection circuits for alarm systems which use standard cables


    The interesting point about all of this, is that of course PoE is a power circuit ... although again BS 7671 is pointing you to the structured cabling standards that are used for that ...


    I would also point out that Blue is not on the list of "control circuit line conductors" either. In BS 7671 and BS EN 60445, Blue is pretty much reserved for Neutral, but telecomms and PoE use Blue for purposes other than an earth-referenced live conductor ... and so do standard wired alarm circuits ... and so does BS EN 60204-1 (which uses blue for DC control wiring, and talks about "light blue" for neutral).

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