grey as earth/cpc?

[tabbypurr]

Can I use some 3 phase SWA on 1 phase, using the grey taped over as cpc? It needs to comply with the 18th.

NT

[Robin]

Until someone comes along with the authoritative answer I'll offer that it was fine to sleeve a core as CPC (although NICEIC et al recommended using the /black/ core to get people away from the idea that black=neutral). I don't know of anything in the 18th to change that but my unknown unknowns are legion.

[John Rumm]

So long as you over mark it at both ends that's fine...

(although it its SWA, then normally using the screen on a two core makes more sense - unless you particularly need the extra CSA)

[Dave Plowman (News)]

Here, the old LEB or whatever moved the meter from the cellar to the top of the cellar stairs, and used 3 phase SWA. With the yellow identified as earth.

I'd use sleeving rather than tape, though. On two wires, both ends.

FWIW, The old to new colours are these:-

Red is now Brown Blue is now Grey Yellow is now Black.

The convention (if there was one) with the old colours was to use red as line, blue as neutral, and yellow as earth. So I'd be inclined to stick with that, so black would be the new ground? With brown blue and green/yellow identified both ends nothing to need guessing at.

[ARW]

AFAIK you can in this case over sleeve the colours in any order you wish and could over sleeve the brown with blue and use it as the neutral if it turned you on and you wanted the extra work.

I would say 99% of installations like this use the black as the cpc:-)