torkell | (Reply)

From:

For the past few decades all single-phase wiring from the plug to the power-sucking-widget has been with the new colours (brown-blue). The core wiring (i.e. from the consumer unit to the socket) for anything done before this year is generally red-black-copper (the earth usually being unsleeved in the wire). It's only been the past year or two that the new colours have really become available, and in fact it's getting hard to buy the old colours now. So unless it's a new installation you'll almost certainly find the old colours.

I'm not actually sure what happens if you swap phase and neutral. I'd imagine most single-phase stuff wouldn't care (stuff like light bulbs doesn't care *what* you feed it as long as there's power there, and modern switching power supplies can sometimes be run off anything from 90v to 250v AC or about 110-300v DC.

I'd guess it would get more interesting with stuff that actually uses all 3 phases. There was one tale I came across of when someone swapped a pair of phases to an olden days hard disk, and the motor ran backwards (which resulted in the heads going down instead of up with the resulting Bad Things that happen when hard disk heads impact the platters).