3 way switch with a dimmer

Hi Jeff, you don't say where the live and switch lines are connected, so I'll try to describe the comlete wiring diagram, assuming the live and switch line enter the circuit at a switch. It doesnt matter what colour wires are in which termnal, just that the continuity is the same. Below is how I do it. At the 2 way switch you will have a wire in each of C (brown or red), L1 (Grey or Yellow) and L2 (Black or blue). At the intermediate switch The L1 and L2 wires are connected in the appropriate terminals, the common wire is connected through the switch via a connector block or push on connector. At the 2 way dimmer The brown or red of the 3 core & earth cable between all the switches is connected to common on the switch. The brown or red of the feed and switch line cable goes in the L1 terminal along with the grey or yellow of the 3 core. The black or blue of the 3 core & earth goes in L2 with the blue or black of the feed and switch line cable. Check the dimmer instructions, as some companies use symbols which you assume is the common, but is actually isn't. One company uses a squirally S which is actually the switch line and not the common. A couple of points to add. All wire must be marked with brown tape or sleeving as they are all "live" wires. If the switch plates are metal, they must be connected to earth, I usually terminate the earth wires in the back of the box and have 1 wire from the termination point to the plate. Hope this works for you, Andy