I came across a 1970s block of flats where the wiring colours were red for live, grey for neutral and green for earth.
Was grey a neutral colour at one stage? The first I have ever seen of this colour coding.
You are easily excited.
Grey was never a neutral colour. It was probably black, either faded or lacking dye in the first place.
It was clearly grey for neutral, all of it, and looks like it always was. This was the house wiring, not appliance wiring.
The earth was green and sheathed, not bare as per normal in twin and earth.
I've seen twin and sheathed earth only once, and that was aluminium wiring. It was green too (predates green/yellow). However, live/neutral were red/black respectively, as normal.
Probably a lot they picked up cheap at the time, then.
Owain
Nevertheless, it would have started out life as black.
Colin Bignell
Must be a pigment of your imagination! ;-)
Grey has never been a neutral colour, although it has recently become a phase colour since harmonisation.
Chances are what you saw was intended to be black, and it was either made to a poor quality standard in the first place, or has lost some of its colour over time.
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Well I recently purchased some 3 core SWA to find the cores to be:
Brown/Live Black/Earth Grey/Neutral
So it would appear grey is *sometimes* neutral.
Info here:
David
"John Rumm" wrote
With the new 3 core and earth - brown, black and grey, I understood that the grey was used as neutral (appropriately sleaved of course).
Phil
Grey is used now with the recently harmonised colours, but it wasn't in the 1970's.
3 core SWA cable is primarily intended for use as a 3 phase power cable where there is no neutral and the armour is used as the earth, and therefore uses the three phase colours of brown, black and grey. 2 core SWA follows the single phase wiring colour scheme and 4 core SWA follows the 'three phase + neutral' colour scheme. I would imagine that it is an economic decision by the manufacturer not to produce two different colour codes for 'single phase 3 core SWA' and 'three phase 3 core SWA', bearing in mind the presumably very limited use of 3 core SWA cable in single phase installations.
As per the TLC website, if using the three core cable for a single phase installation you should oversleeve the neutral and earth conductors with blue and green/yellow sleeving respectively.
Cheers
Chris
The cores are those colours because that's what BS 5467 requires. Brown black and grey are now the three phase (line) colours for 3-phase fixed installation wiring (BS 7671, harmonised with IEC 60364).
The most common application of 3-core SWA is probably for 3-phase,
3-wire circuits (e.g. motor circuits where no neutral is required) and the core colours match that. If you choose to use it in a single-phase installation you must apply appropriately coloured sleeving at the terminations to identify the conductors. Convention is to use the grey core for neutral, as you've already noted.The same situation arises with 3-core & earth flat PVC cable, commonly used in single-phase lighting circuits. This also has brown, black & grey cores and must also be appropriately sleeved.
FYI for single-phase you could have used 2-core SWA. The armour copper-equivalent CSA complies with Table 54G of BS 7671 for all sizes up to 95 mm^2, so is entirely adequately sized for use as the CPC (earth).
Red Silver Green or Red White Green are colours that have been used in the USA, sounds like someone made a deal round the back gate of a USAF base!
Andy
When used in a single phase setting for live neutral and switched live I believe that is the preferred choice (leaving brown as a live and discouraging people from thinking of black as a neutral). Used in three phase set-ups it will be as the name suggests obviously.
I meant it wasn't back then.
Could it be double sleeved single with black as the inner sleeve?
You should have seen the mess when the grey wire appeared!
Danz
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