You are replacing some old-fasioned light fittings (that look like inverted 1970s pub ashtrays screwed to the ceilings) with shiny new LED dome fittings. The house is wired in T&E with red and black cores and you find that the switched line feed is coming into the existing fitting as a black core in a T&E. Mostly you have found that these have been nicely oversleeved in red, but one or two aren't.
Would you :
a: Oversleeve/mark in red to be consistent with the existing wiring
b: Oversleeve/mark in brown as that is the common 'current' colour for a single phase line conductors
c: Leave it as black as that is an allowed 'phase' colour these days......!
d: Something else - if so what?
Jason.