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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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    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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    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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