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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

    It may very well not break any rule, but in someways it would be better if they were all brown, and then at least folk would check

    Actually deliberately cycling phases is common, to balance the load, as single phase lamps and controls nearly always seem to be on phase 1 (let's call it brown) when machines are built.

    Cylcling 1>2>3  or 2>3>1 or 3>1>2   all go the same way.

    Reversing the sense of circulation so 1>2>3>  becomes 3>2>1 is less desirable, as that way machines go the wrong way, and cooling fans suck when they should blow and so on.

    I suggest that some extremely clear labeling or over-sleeves  wil be needed of brown goes in and comes out grey  but black is black..

    M

  • 0 in reply to mapj1

    Hi there - many thanks. Yes, we have some air-supported structures that use 'blowers' (fans) to keep them up, so phase sequence is definitely important to us!! In our case, the labelling of conductors is good - but I take your point that to tolerate any departure from the "preferred" colour seqeuncing (Brown, Black, Grey) demands excellent labelling. Cheers.

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  • 0 in reply to mapj1

    Hi there - many thanks. Yes, we have some air-supported structures that use 'blowers' (fans) to keep them up, so phase sequence is definitely important to us!! In our case, the labelling of conductors is good - but I take your point that to tolerate any departure from the "preferred" colour seqeuncing (Brown, Black, Grey) demands excellent labelling. Cheers.

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