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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!

Parents
  • 0

    Please realise that the L1,L2,L3 is arbitary

    Agreed. As far as I've been able to tell there's not even a standard as to the rotation of R/Y/B (or L1/L2/L3) coming in from the street - each area seems to have own historical convention. I understand that there's one area around York for example that has the reverse rotation compared with surrounding areas - and it's not easily standardized without taking a huge risk with all the existing 3-phase motors.

       - Andy,

  • 0 in reply to AJJewsbury

    Thanks Andy - I mentioned above that we have some air-supported structures that use blowers (fans) to keep them inflated - phase rotation is very important to us! We really don't want air being sucked out rather than pushed in ... cheers!

  • 0 in reply to Fraser Donachie

    Indeed - it's important to lots of people, yet BS 7671's precise colour coding scheme doesn't actually help at all. If your company had two sites, one in York and another in Kent, both installations wired identically using the precise L1=brown, L2=black, L3=grey notation consistently throughout, you'd still run the risk of a motor running backwards if you transferred it between the two sites.

    From my local DNO (https://www.northernpowergrid.com/asset/0/document/103.pdf )

    The phase sequence at each system voltage is represented vectorially by R-Y-B anticlockwise rotation with the exception of the 11kV and LV system in the City of York and the LV (fed from 11kV) system in Middlesbrough, which are represented by R-Y-B clockwise rotation.

    I guess other areas have their own examples.

      - Andy.

  • 0 in reply to AJJewsbury

    Cheers Andy - the NPG pdf is interesting! It's not something I've ever considered but is a great example showing that the phase rotation can differ from location to location. I guess this is very much an inheritance from 'pre-history' that can never be practically standardised due to the high cost; e.g. on the Foss Islands Retail Park! Thank you again - F

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  • 0 in reply to AJJewsbury

    Cheers Andy - the NPG pdf is interesting! It's not something I've ever considered but is a great example showing that the phase rotation can differ from location to location. I guess this is very much an inheritance from 'pre-history' that can never be practically standardised due to the high cost; e.g. on the Foss Islands Retail Park! Thank you again - F

Children
  • 0 in reply to Fraser Donachie

    In the U.K. L1 should be RED, L2 should be YELLOW and L3 should be BLUE as seen on millions of external transformers nationwide.. Obvious bright and logical colours, not dinghy dark similar and often misidentified colours.

    www.youtube.com/watch

    M.E.M. ruled....O.K. and still does.

    Z.

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