I'm fitting an extractor fan but struggling with the wiring layout in the room, the lighting supply comes from a junction box in the next room (outbuilding conversion) i can get a supply to the fan location, but i'm struggling with the switched live (timer fan) i can't get access to the switch wire, which runs from pullcord to ceiling fitting, is there any way around this, the supply to the ceiling lght fitting also comes from the junction box in the next room, so i can access both supplies but not the switch wire, Don't know if i've explained this clearly