Thanks for posting that C-H. I hadn't yet heard about the schedule for the change, although I know it's been talked about for some time.
I have to agree with David's concerns over the possible confusion. When the U.K. adopted the Continental colors for flexible cords in 1970, we were left with blue in fixed cables still being a phase and blue in a new flex being neutral. (Older flex could still have blue as a phase!) Confusing enough?
In a conduit installation, if somebody opens up a box and sees brown/black/gray/blue instead of red/yellow/blue/black, they'll recognize it as the new system (we hope).
But what about where all phases are not present? The IEE Regs. have for decades specified that red be the phase on single-phase ciorcuits, with an exception that yellow (formerly white) or blue may also be used before the final distribution panel to help identify phases.
Open up a box on an older single-phase feeder in such a system and you may be confronted with just blue and black. Problem: Is this an old system with a blue phase and black neutral, or new wiring with a black phase and blue neutral?
Sure, anyone messing around in 3-phase commercial systems is more likely to know what he's doing than the average householder, so if there's any doubt he should check.
For residential wiring, I suppose that having the colors the same as for appliance cords makes sense in a way, but I can see the DIYers getting into all sorts of muddles when confronted with the two systems side by side.
The point about black and brown is valid as well. We already have 4-core flex used on control circuits etc. in which the fourth wire is black. It is sometimes quite difficult to distinguish it from the brown when working in a dark corner. If we could make sure that the brown used in a black/brown/gray phase arrangement is a light brown, then it would be helpful.
I agree, though, that our present red/yellow/blue, the older red/white/blue, or the American black/red/blue makes for colors which are more easily distinguished.
Is there really any need to change?
[This message has been edited by pauluk (edited 05-06-2003).]
