My elderly neighbour has a broken pull cord fitting in the bedroom and asked me to change it for him, he doesn’t want to pay as he is on a small pension. I have bought him a two way pull cord but when I came to unscrew the old one, the wiring wasn’t the usual colouring on the wires. There are two cables coming through the ceiling, one has just a black wire the other cable has two wires one red and one black. These have been connected to the block separately but I don’t know how to wire these into the new fitting. The red is live and the black is neutral but what is the other cable wire and how do I fit them correctly.