Wiring a bathroom extractor fan

[Taylortwocities]

i suppose with installing the switched fused spur i have the isolator there

Well, it'll serve as a fan on/off switch, I suppose. But it won't isolate the fan as it is connected to line, switched line and neutral.
These three are all defined as live conductors, and an isolator has to break all three to properly isolate the device.

But you are where you are now, but you'll have to decide which two of the three will you run through the fused switch. Really the easiest place to get all three (plus earth) is from the light itself - not the switch - as shown in the Vent Axia diagram in post #13.

 

[chuckstre77]

ok, i think i get you. The fused spur isnt needed (as you said earlier) , but instead buy a fan isloator switch.
Put a junction box (or similar) in one of the cables in the loft from one of the lights and take that down to supply the switch with L, N & E.
And then feed out of the isolator to the fan with L, SL , N as no earth is needed.

Thanks for your patience, i can usaully work these things out but dont want to risk getting this one wrong.

Changing things around isnt an issue if needed, ive got the room, time & patience

 

[Harry Bloomfield]

well, it said douple pole fused spur, so i bought one with a switch so i could turn the fan off if the timer function wasnt needed at times like the middle of the night when the wife goes for a pee about 20 times

An extract fan, in a bathroom, which has a window - relying on the light to be switched on, to run the fan, has limited usefulness. It means the fan is only certain to be run, when it is dark, and the light needed. Much more sensible, is a PIR triggered fan.

No doubt you were exaggerating, with the '20 times', but having the fan run at odd times is not entirely wasted, in a bathroom. High moisture levels can linger long after a shower or bath. The fan being triggered intermittently a few times after, can only help reduce the moisture, and avoid mould.

 

[chuckstre77]

So your saying to put it on a seperate switch so it works independently of the light switch

 

[Harry Bloomfield]

So your saying to put it on a seperate switch so it works independently of the light switch

Who, me?

I'm suggesting they are best PIR triggered, so anyone walking into the room, triggers the fan to on, irrespective of whether the light is on or not. Then if someone takes a bath, fills the room with moisture, maybe during the day, without turning the light on - you can be sure the fan will run, to clear the moisture.

Cost of running a fan for 20 minutes is miniscule - maybe 0.23p. That versus the cost of mould, cleaning and decorating.

 

[chuckstre77]

Yeah, that’s fair enough. I’ve already bought the fan with a timer. Thanks for your input tho. It’s all valuable.