The Irish regs require that the 1st phase in 3 phase is always to be brown... and that single phase will always be blue (N) brown (Live) This means that you'd never find a single black cable as a live conductor.
We also have lots of Red & Black cable installed as well as our old unique irish 3-phase colour system.
If you come across brown, black grey it will be together and very obviously 3-phase.
