Hi Rich, been pondering this myself. Had a dig through all my french references yesterday but found no written reference to wire colour. I did find some colour photo's of unrestored a/c that showed the wires in natual tone, but were these original? Wires are/were replaced on a regular basis for maintainance, so maybe blue when the a/c was new from the factory but not when wires were replaced?? Will keep digging. Regards, Pete in RI