Simple phase colour question

[ericmark]

Before the harmonisation rest of Europe had brown, black, black as the three phases, it was a real pain getting motors to turn in the correct direction and a phase rotation meter was a needed tool, it would seem during the war a bomb on Liverpool hit a cable and when repaired the phases were swapped so instead of red, yellow, blue they had red, blue, yellow and it stayed that way for many years after the war.

Since I had a phase rotation meter it was my way to test all sockets and ensure they were correct, however this only works when the factory is correct in the first place, and surprised how many are wrong. When working with concrete pumps and 32A three phase sockets, having one lead made wrong was like a disease, as invariably it would be corrected in the wrong place, so again the phase rotation meter was important.

Today the use of inverters has removed the problem of phase direction.

It seemed a pity when we went to Brown. Black, Grey the old saying Red to Red, Yellow to Yellow and Blue to bits does not work with grey.

 

[ban-all-sheds]

As for the switch in my hallway, 2 sets of red/blue/yellow or even 2 sets of brown/black/grey would be easier to cope with than 6 bloody brown conductors in my view! I did my best to remember what went where and did bugger it up once but I know how 2-way lighting works and knew what I had probably done wrong so I got there in the end

 

[sparkwright]

I've established that brown/grey/black are the colours used to identify the 3 phrases now, as they are the colours used in 3 core cabling. OK Then.

For anyone interested about my 2g-2way light switch change, my lighting has been wired with looped singles, so the line is looped at the switch and the neutral at the ceiling rose. This didn't affect me changing that switch though, it was the sea of bloody brown wires (ha, racist much?)
I did try remember which conductor went where when I removed the old switch, but the fact that all 6 bloody conductors were brown made it a bit difficult and I did mix a strapper up with a perm live, for instance!

As you've gathered by now,
L1 red = brown
L2 yellow = black
L3 blue = grey
N black = blue

As you can see, black for neutral has become L2, and blue for L3 has become neutral.

In a 3 core household cable where neutral was required, the norm was to use the blue. As you can see, grey should now be used, sleeved blue.

 

[JohnW2]

In a 3 core household cable where neutral was required, the norm was to use the blue. As you can see, grey should now be used, sleeved blue.

I've often wondered why 'household' 3C+E used (both 'then' and 'now') phase colours. I've only ever seen it in 1.0mm² and 1.5mm², and find it fairly hard to believe that it was/is ever used for 3-phase (without N) applications. For 'household' use, something like red/red/black (or brown/brown/blue) would seem more logical, and likely to result in far less uncertainty and questions being asked!

Kind Regards, John

 

[ericmark]

I've often wondered why 'household' 3C+E used (both 'then' and 'now') phase colours. I've only ever seen it in 1.0mm² and 1.5mm², and find it fairly hard to believe that it was/is ever used for 3-phase (without N) applications. For 'household' use, something like red/red/black (or brown/brown/blue) would seem more logical, and likely to result in far less uncertainty and questions being asked!

Kind Regards, John

It is the same with yellow arctic cable, it is used for 110 volt systems, which don't have neutrals and have not had neutrals as far back as I can remember so why do they have a blue core, should be brown, black and green/yellow can't even say designed for USA as they have a completely different colour scheme.

 

[sparkwright]

I've often wondered why 'household' 3C+E used (both 'then' and 'now') phase colours. I've only ever seen it in 1.0mm² and 1.5mm², and find it fairly hard to believe that it was/is ever used for 3-phase (without N) applications. For 'household' use, something like red/red/black (or brown/brown/blue) would seem more logical, and likely to result in far less uncertainty and questions being asked!

Kind Regards, John

Seems logical enough to me. 3 core flat cable would have been invented primarily for 2-way lighting circuits, which would consist of three live wires, so would be logical to use phase colours.

Using a 3 core flat cable for live, switch live and neutral wouldn't have been such a priority, and timed extractor fans weren't used then.

 

[JohnW2]

Seems logical enough to me. 3 core flat cable would have been invented primarily for 2-way lighting circuits, which would consist of three live wires, so would be logical to use phase colours.

Fair enough, but I still do not see the logic in having three different phase colours in a cable which was virtually always going to be used in a single-phase application - so I suppose that 'treble red' (treble brown these days) would have been the most logical.

Using a 3 core flat cable for live, switch live and neutral wouldn't have been such a priority, and timed extractor fans weren't used then.

Agreed. I did not think enough before suggesting red/red/black (or, now, brown/brown/blue) - as above, 'treble red' (now 'treble brown') would probably be more appropriate (give or take the problem in working out which was which!).

Kind Regards, John

 

[sparkwright]

I suppose it would be a bit pointless having even more colours to denote the phase conductor, and no doubt cost comes into as well.

One could have all the cores the same colour, and numbered, but different colours is perhaps more luxurious.

I wonder if a 3 core+earth flat cable has been used for a three phase application?

Years ago on this site, a respected member mentioned this would be acceptable, though it's something I would choose to avoid.

 

[Iggifer]

I'm sure there are plenty of occasions where it has. I haven't seen it personally but judging by the state of a lot of independent factories/machinists I would not be surprised.

 

[JohnW2]

I suppose it would be a bit pointless having even more colours to denote the phase conductor, and no doubt cost comes into as well. One could have all the cores the same colour, and numbered, but different colours is perhaps more luxurious.

All true. However, we did have red+red (now brown+brown) and managed with that (and it obviously does sometimes matter 'which is which').

As for 'which is which', rather than numbering, as you will know, at least some makes of red/red and brown/brown had/have white insulation below the brown for one of the conductors, so I suppose one could have two different 'inner colours' for brown/brown/brown (the third being 'solid brown')..

I wonder if a 3 core+earth flat cable has been used for a three phase application?

As I said before, I would have imagined that that virtually never happens, particularly give that it appears that the biggest size of flat 3C+E (at least now) is 1.5 mm². That, of course, was my main reason for thinking that the choice of colours was perhaps not the most obvious.

Kind Regards, John