I'm installing a ducted extractor fan with run-on timer in my loft to give extra steam extraction for the bathroom. The bathroom has an opening window so I want the fan to be switched separately totally independent of the light (don't want to have to turn the light on if it's daylight, and don't want the fan to run unnecessarily every time you turn the light on). There will be no wiring in the bathroom itself as the fan is up in the loft and I want a wall switch outside the bathroom to turn it on/off.
I know about the fan needing a permanent live (3 core + earth from the junction box etc) but want to know if I can use a 3A fused double pole switch on the landing as a simple on/off switch. Thinking ahead when decorating the landing some months ago, I already chased out and installed a back box outside the bathroom and 2 core 1mm cable up into the loft, so want to keep this arrangement if possible. I keep reading about fans needing a fused isolator outside and then another pull switch inside the bathroom, but I just want to be able to turn the fan on/off as required from outside on the landing and have it run on a few minutes after I switch off.
The wiring diagrams supplied with the fan all assume you're linking it in with the pull cord light switch and I can't find any info on having the fan independent.
Any help appreciated!