A Question about Wiring Colour Code Conventions

[Paul_C]

Am I the only oone who remembers the leaflets and posters advising of the changeover to harmonised colours, the picture of a 3 core swa clearly showed the black sleeved blue and grey sleeved green/yellow.

No, I recall seeing that too.

Following some of the instructions in this thread would mean:-
P1 = BROWN
P2 = BLUE SLEEVED BLACK
P3 = BLACK SLEEVED GREY
and 5 core 3p & n & e:-
P1 = BROWN
P2 = BLUE SLEEVED BLACK
P3 = BLACK SLEEVED GREY
N = BLACK (OR WHITE OR YELLOW OR ORANGE) SLEEVED BLUE

Which would be compliant with the regs., of course, but quite unnecessarily convoluted when you could do it by using some of the cores "as is."

I really don't understand the argument that just because R-Y-B was usually used as L-E-N (respectively) in single-phase applications that there should be any sort of association of L-E-N with the L1-L2-L3 phase colors directly. It makes no sense whatsoever to me, since we're talking about two different things.

'

 

[Paul_C]

Do the regs not say that if 3 wires of the same colour are used for 3 phase they must be identified at their ends?

Yes, if all three are brown then they should be identified appropriately.

In my view, and it is my view which I know is not shared, as black and grey (or yellow & blue) are phase colours, denoting a 240v conductor there is no need to sleeve them brown when used on a single phase circuit such as 2 way switching, they certainly never used to be.

I agree. Although the regs. say they must all be identified brown (or red prior to the change), for all practical purposes you know that in a 2-wire 1-phase system they can't be different phases or poles, so there should be no room for confusion.

 

[SUNRAY]

Which would be compliant with the regs., of course, but quite unnecessarily convoluted when you could do it by using some of the cores "as is."

I really don't understand the argument that just because R-Y-B was usually used as L-E-N (respectively) in single-phase applications that there should be any sort of association of L-E-N with the L1-L2-L3 phase colors directly. It makes no sense whatsoever to me, since we're talking about two different things.

'

I'm with you on this, I still tend towards black as neutral in a 'mixed colour' installation but grey in 'all new colour'

 

[SUNRAY]

having seen this drawing

and this one:

I see that the theory of using the colours of 3c&e on the basis of the position in the cable is only applied in some situations.

Thanks BAS for highlighting them.

 

[Spark123]

The bottom one is wrong in that it should have sleeving on the conductors to indicate they are switch live wires, it is in the appendix of BS7671:2008 (as it is harmonised it says brown - but I wouldn't hink twice about passing red on an old colour system.)

 

[ban-all-sheds]

In my view, and it is my view which I know is not shared, as black and grey (or yellow & blue) are phase colours, denoting a 240v conductor there is no need to sleeve them brown when used on a single phase circuit such as 2 way switching, they certainly never used to be.

I agree. Although the regs. say they must all be identified brown (or red prior to the change), for all practical purposes you know that in a 2-wire 1-phase system they can't be different phases or poles, so there should be no room for confusion.

514.3.1 is quite clear and unambiguous. Apart from concentric conductors, metal sheaths or armours used as cpcs, bare conductors where permanent identification is not practicable and extraneous- or exposed-conductive parts used as cpcs, conductors shall be identified by colours or letters as per 514.4/5.

In other words no matter what you know, in a single phase application, black and grey cores used for line shall be sleeved brown or labelled "L" - it is not optional.

 

[ban-all-sheds]

I see that the theory of using the colours of 3c&e on the basis of the position in the cable is only applied in some situations.

Thanks BAS for highlighting them.

I didn't draw those illustrations...

 

[Paul_C]

In other words no matter what you know, in a single phase application, black and grey cores used for line shall be sleeved brown or labelled "L" - it is not optional.

I acknowledged that's what the regs. demand, just as before the change they said that yellow & blue cores shall be sleeved red where appropriate.

 

[ban-all-sheds]

Yo - I was really replying to both you and Sunray, who said

In my view, and it is my view which I know is not shared, as black and grey (or yellow & blue) are phase colours, denoting a 240v conductor there is no need to sleeve them brown when used on a single phase circuit such as 2 way switching, they certainly never used to be.

because that's not just a view "not shared", it's a position clearly in contravention of BS 7671, and is also plain wrong about the "they certainly never used to be".

And even though you acknowledged what the regulations require your initial response was to agree with him....

 

[Paul_C]

Fair enough. I think the point being made is that while the Regs. have long demanded sleeving (red, then brown), at one time it was very common practice not to bother to sleeve things like 2-way travelers on a regular single-phase domestic installation.

I'd say that unsleeved yellows & blues (or whites & blues) on 1960's installations were far more common than sleeved ones. Ditto for unsleeved black switch returns on a regular 1-way.

 

[ban-all-sheds]

No more common than unsleeved blacks and greys in 3C+E, or unsleeved blues in switch returns are nowadays...

 

[SUNRAY]

No more common than unsleeved blacks and greys in 3C+E, or unsleeved blues in switch returns are nowadays...

Oh no
In think i'm safe in saying that the first time I saw a marker on a cable was well into the 70's.

Despite what my posts may infer, these days I would not dream of using unmarked wires. As the bulk of my work is in controls, I tend to use numbers and letters rather than coloured sleeves.

 

[csh]

Slightly off topic , but why does 3ce flat grey cable not have a blue core instead of the grey one. This would rule out a lot of confusion when one core is used as a neutral conductor.

 

[RF Lighting]

Because it is not always used as a neutral such as with 2 way switching, or a 3 phase supply (although not really the best cable for 3 phase)

 

[SUNRAY]

Slightly off topic , but why does 3ce flat grey cable not have a blue core instead of the grey one. This would rule out a lot of confusion when one core is used as a neutral conductor.

It does tend to be used more for live only applications.

If you want to buy it in large enough quantities its available in any combination you want.

We once had some 2.5mm7x twin made and for the manufactures convenience it was red and brown.