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Three Phase AC Phase Conductor Colours - Mandatory?

Fraser Donachie

An LV Switchgear manufacturer has correctly used Brown, Black and Grey conductor colours in their panels. But the assignment is not the "preferred" L1=Brown, L2=Black & L3=Grey. Instead, the phase sequence is different. Whilst this is extremely undesirable from a safety and human factors viewpoint, is it 'illegal' or would it mean their DofC is invalid? IEC 60445 does not specify the assignment between L1, L2 & L3 and Brown, Black or Grey. I believe CENELEC HD 308 S2 may specify the "preferred" assignment but I cannot obtain a copy of that. How mandatory is the "preferred" and generally accepted assignment L1=Brown, L2=Black & L3=Grey? THANKS!

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  • 0

    Also worth noting for some panels, if BS EN IEC 60204-1 applies (machinery as defined in the Machinery Directive, including machinery control panels and drives), colours are different to BS 7671, and the standard has some requirements that over-ride BS EN IEC 60445.

    This is a good article which discussed the differences regarding FE and line conductors: www.gt-engineering.it/.../shall-a-basic-safety-standard-be-applied-to-machineries-the-case-of-pink-functional-grounding-cable

  • 0 in reply to gkenyon

    Be careful Graham, you are opening another huge can of worms, leaving one with the impression that no two "standards" are in any way standard with one another, and the whole lot is a massive mess! I will make no opinion, but from experience this pretty much applies across the whole gamut of EU alleged "standards". On the whole BS7671 is comparitively good to excellent, although still suffers from feature creep in unintended ways. This is probably because a single committee (JPEL/64) has the final say and others like you keep up the reminders about all the interacting standards, thanks!

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  • 0 in reply to gkenyon

    Be careful Graham, you are opening another huge can of worms, leaving one with the impression that no two "standards" are in any way standard with one another, and the whole lot is a massive mess! I will make no opinion, but from experience this pretty much applies across the whole gamut of EU alleged "standards". On the whole BS7671 is comparitively good to excellent, although still suffers from feature creep in unintended ways. This is probably because a single committee (JPEL/64) has the final say and others like you keep up the reminders about all the interacting standards, thanks!

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  • 0 in reply to David Stone
    David Stone said:
    Be careful Graham, you are opening another huge can of worms

    I'm just sharing what I know

    David Stone said:
    leaving one with the impression that no two "standards" are in any way standard with one another

    If you're referring to BS EN IEC 60204-1, well, there are some very good reasons why the standard should be the way it is, and each part of the machinery (including control panel) should be supplied with a schematic, and wiring numbered to avoid confusion. A control panel would be equally confusing in terms of "uncontrolled mains in" vs "mains out per phase" (e.g. to motors) and "auxiliary per phase" (AC controls).

    However, it might surprise you to know that, whilst BS EN IEC 60204-1 might look slightly different (e.g. all black conductors for each phase or line conductor in single phase systems), it does actually align with BS EN IEC 60445, in that black is a permitted line conductor colour - neutral is still blue, protective conductors still green-and-yellow, and the other colours identify specific functions of the conductor relative to the machinery or control panel.

    However, not sure what all that has to do with the fact that you're seeing L1, L2 and L3 on equipment terminals, when the standards say they should be U, V and W? That goes for BS EN IEC 60204-1 as well as BS EN IEC 60445 and BS EN 61666 (the latter two being referenced from BS EN IEC 60204-1). BS EN 61666 is terminal identification in industrial equipment, and aligns with BS EN 60445 on the use of U, V and W.

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