The wiring circuits in my flat were laid out when the reinforcing cages where put together for the concrete frame- they used steel pipe of around 1/2" diameter, through which the wiring is run.
The lighting circuits are Live and Neutral, red and black single core.
In the ensuite there is a ceiling rose, and then (previously) a steel pipe ran down to a switch.
I've cut the pipe off, so just have the L&N wiring coming from the stub of pipe in the ceiling.
I had run that into a switch outside the ensuite by the door.
My intention was to use that L&N to power the extractor- but it looks like I need to connect into the L&N before the lights, if that makes sense, rather than after them, as I am now.
It does make sense. My thoughts would be to wire it as per your drawing but the convention seems to be to pick up the live and neutral from the ceiling rose before the light switch and run it to the fan via a double pole isolator. The switched live then comes via the light switch but is unaffected by the isolator. Mine, in a 10 year old house, are all wired this way as are all the other recent 'professional' installations I've happened upon.
I guess the reason for this is that the fan can be isolated without affecting the bathroom light. The danger is that you have the potential for a live feed if you isolate the fan to replace it but have the bathroom light on.
It does make sense. My thoughts would be to wire it as per your drawing but the convention seems to be to pick up the live and neutral from the ceiling rose before the light switch and run it to the fan via a double pole isolator. The switched live then comes via the light switch but is unaffected by the isolator. Mine, in a 10 year old house, are all wired this way as are all the other recent 'professional' installations I've happened upon.
I guess the reason for this is that the fan can be isolated without affecting the bathroom light. The danger is that you have the potential for a live feed if you isolate the fan to replace it but have the bathroom light on.