correct cable colours

[Notasparki]

In an extraction fan installation, what is best practice or regs for cable coluring. ie switched live, perm live and neutral, which colour, brown, black and grey. should go to which.
Thanks

 

[ebee]

For the New "Killer Colours" then

Brown = permanent L
Black (sleeved Brown) = Switched L
Grey (sleeved Blue) = N

The Old Colurs were

Red + L
Yellow (Sleeved Red) = Switched L
Blue (Sleeved Black) = N

Anthough in R Y B the Blue was often not sleeved Black in practice and left as Blue = N