Hmmm..... Why would somebody have done it that way, I wonder? If there is a need to identify circuits belonging to each apartment (maybe in a floor/celing void where there are conduits for the apartments both above and below), then I would mark the actual conduits at strategic points with tape or paint.
Nothing like that... It's just each circuit running in its own conduit up from the basement to the meters for all shops/apartments in the basement and on the ground floor. And it's only the three-phase circcuits that are coded like that, the single phase use the "whatever they had" scheme.
