Downunder in NZ
Single phase
Phase Red
Neutral Black
Earth Green/yellow
3 Phase
Phases Blue, White, Red,
Earth Green/yellow
However Flex cables can be different with Brown and Blue for phase and neutral in single phase leadout cables.
Much better 3-phase colours than the new dull colours (black/brown/grey) we were forced to change to (though we had yellow instead of white).
It makes you wonder how many mistakes are made (or will be in future) when cables end up dirty & illegible.
David
Yellow is sometimes used for phase in 3 ph too here.
About the 2 pole mains Black and Blue you mentioned, obviously a UK sparky couldn't bring himself to use the Black for phase as the US do so used the Blue like you would for 3ph.
Sorta makes sense for us that don't use Black for phase.
But we now do use black for a phase, makes me glad I'm not a sparkie.
(Attachment Link)
David
In the U.S. houses I see black and red as 220V line with white neutral and green or green/yellow or bare copper as ground.
In an industrial setting I see black as three phase line maybe with white,black,red terminal insulation/markers.
Then red - hot 120v. white - neutral.
And blue - DC 24V everywhere. Then the deadly yellow - power from around the corner down the block or that panel in the next building over.
Then more black for whatever motor spins everything.
and the same green or green/yellow or bare copper - ground.
Or in the old Hot Rocks warehouse white neutral. Red,black, and green three phase lighting power. Conduit was ground. Tried to object to working the lighting as out of my assigned area but boss said "The whole plant is your area."
They never wrote me up for being out of my area. I had the run of the whole place, roof, basements, breakrooms, outside, tunnels.....