Identification of conductors (appendex 11)

[Gerry]

Table 11a (osg) lists all the colour configurations for all standard cable types, this is straight forward. My question is :- When using 6243Y (flat three core & earth, Brown, Black, Grey & bare CPC). Which core would you sleeve as the switch wire and which one as the neutral when your using one core as a feed, one as a switch wire and one as a neutral. Seems a simple question but the only thing I can find is App 11.4 and this only relates to using the cable as an intermediate or as a two way. My tradesman says the grey should be marked as neutral (blue sleeving) and black (brown sleeving) for the switch wire. Does anyone know the specific regulation covering this or is it a case of common practice.

 

[Adam W]

Is it for a PIR switch?

There are no specific regulations relating to which way around the black and brown go, which causes a big debate on here every now and again.
I'd use grey (sleeved) for neutral, brown for permanent live and black for switched live.

For light fittings however I would use black for the permanent (emergency) live and brown for the switched live, because the black cable would go into the 'A' terminal on a rose connector. I do it like that because the manufacturers do.

 

[Gerry]

Yes mate, the customer wants pir's everywhere.

 

[Adam W]

Then yeah, up to you.
If the pirs come preflexed you'll probably find they've used black for the switched live and brown for the feed, but check the manufacturer's data.
Grey should be used for the neutral though.

 

[jeremy]

I do Brown/Perm Black/Switched, Grey/Neutral. I do this so there is an earth between any line conductors and neutral but worked this out for myself, no-one's ever told me one way or the other, would like to know if there is a given way.

 

[Guest123]

I think the only real guidance we had was when the clours were harmonised.

The NIC wrote a article on "de-neutralising the black" and suggested we were to start sleeving the grey conductor as neutral and black as either your other line or CPC in the case of a 3 core SWA used for single phase applications.

 

[Andyfm]

Lenny, what was the NIC article saying were the reasons for not using black as neutral (i`ve not read it) because its never seemed obvious to me.

 

[Sintra]

Under the new legislation colours for fixed wiring introduced by Amendment 2 to BS7671, black is now used to identify a phase conductor, not a neutral conductor, in new installation work.
for all single-phase applications, it is required use cables marked for such use, that is with brown, blue and green-yellow cores.
Breaking the black/neutral association
Where three-core cables, marked in the new three-phase colours are used for single-phase applications, it is proposed that, as a convention, the black core is used for the protective conductor, the brown for the phase conductor and the grey for neutral. This convention is intended to break the association between black and neutral. It would mean that the black core would normally be over-marked green-yellow, and the grey core over-marked blue or N. The brown core would not need additional marking.

Quote from NICEIC.

 

[Andyfm]

Is this a case of the NIC just being awkward for the sake of it - in the old colours, blue was used for neutral in single phase armoured or 3c+e, even though it was a phase colour in TPN , I` ve just never seen the sense this grey as neutral, and on a mixed colours job, to me it make more sense to use black as neutral.

 

[Adam W]

The old colours were
Red - Yellow - Blue (in that order). Harmonised colours
Brown - Black - Grey (in that order) making grey the new blue.

 

[Johno]

but blue wasn't neutral

 

[Johno]

I know the guidance says use grey as neutral, but I still use black as neutral.

I suppose it don't really matter as long as you sleeve it.

 

[Sintra]

In the regs it doesn't matter what cores you use so long as they are sleeved correctly but i can see the logic in using the grey for neutral and not the black.

 

[Johno]

I can see logic in both, but as said it don't matter as long as it is sleeved/identified.

 

[Des 56]

I may be wrong,but I think this grey for neutral belief came about because of the Niceic s lust for making their own regs

They want to use grey as the neutral so that black,being a phase colour,is no longer associated with neutral

What the logic behind this I dont have a clue,but sometimes they are a difficult organisation to understand