Anyways, here's an electricians Sudoku:
I have a two way switch for my hallway. One upstairs, one downstairs. The light is upstairs. Back box upstairs has three core coming in from above ( brown, black, grey, earth). All browns are together in choc block terminal, all greys are together in choc block, so I have only ONE BLACK wire ( brown sleeve ) left to use from that three core. I'm puzzled cause all diagrams show two wires to be used and connected to switch.
There is three core between switches with one black( brown sleeve) and one grey ( brown sleeve ) left to be used. The brown is in choc block.
Three wires, but I can't figure it out!