Kent:
I've never heard of metal fixture boxes which are then insulated. We've certainly never used anything like that here.
We adopted the common European brown, blue, green/yellow colours in 1970, but only for flexible cords. Fixed wiring cables continued with our old system of red for phase, black for neutral, green for ground.
Green/yellow is now used for ground on fixed cables as well, but we still use red and black.
When flexibles are used for 3-phase now, all 3 phase conductors are brown, and we also use letters or numbers to identify them if phase rotation or identification is important.
Do I take it that black, brown, and white are your standard colours for 3 phase fixed wiring? Ours are red, yellow, and blue (since 1965).
Yes, houses in the U.K. normally get a single-phase 240V service, rated at 100A on almost all new houses, although a lot of older 60 and 80A services are still in use, and even a few 40A ones.
I think 3-phase for residential use is quite common across Continental Europe, isn't it? I know this is certainly the case in France, where I have seen some houses with a 3-phase supply of as little as 15A per phase.
"Twin & earth" is the cable used for 99% of residential wiring in England. It consists of an outer oval-shaped PVC sheath in grey or white, containing two PVC-insulated wires for line & neutral between which is a bare copper ground wire. We also have "triple & earth" which is used for 2-way light switching, etc.
"Romex" is the American equivalent, but with a different colour code. In case you didn't know, in America they use black for phase and white for neutral.
