Hi all, Just moved into a house with an old (16 years-ish) cbus system, one of the rooms (en-suite bathroom) recently stopped working and im going slightly insane trying to figure it out. One of my many questions is, on the relay each output has an a and a b (1a 1b, 2a 2b etc..) - is there a differerence between these? The current wiring that is relevant is: 7a - output to main bathroom and a wire linking to 8a 7b - output to main bathroom 8a - wire linking to 7a 8b - output to en-suite bathroom that doesnt work I dont understand the bridge between 7a and 8a or why its suddenly stopped working - everything else is fine. The light comes on solid green on the relay when button is pressed both on the switch and from the relay Also - is there a good source of documentation about the relays that anyone has? Everything i've looked at is pretty basic. Thank you! Mark