Installing an extractor fan

[bitslice]

Can I just say that I hate sitting there with a fan buzzing away, I'd rather have these things on a timer after I've left.

 

[Participant]

You'll have to use a separate FCU as the manufacturers will specify that with either a 3/5amp in, plus a fault in it would take out the lights too, you don't want that.
It's easy & cheap enough (FCU's @£4) to do & the FCU & isolator can be in the loft area.
As it's a timer model, wire it like this -

2 core L/N from lights to FCU
2 core L/N from load side of FCU to 3 pole isolator, bridge L to Perm L on supply side of isolator.
Perm line & neutral from isolator to fan
Switch line to pullswitch in bathroom, then on to fan.

Hope that makes sense

Brilliant, cheers. Having a 3 pole isolator in the loft but retaining the ability to knock the fan off with the existing 2 pole pull cord in the bathroom sounds like a good option. Though I'm still not sure of the purpose of the 3 pole isolator when I can just knock it off at the MCB.

Can I just say that I hate sitting there with a fan buzzing away, I'd rather have these things on a timer after I've left.

Agreed, but this is a centrifugal in-line fan that will be on a rubber pad in the loft, so I doubt there'll be too much in the way of buzzing.

 

[JohnnyG]

Brilliant, cheers. Having a 3 pole isolator in the loft but retaining the ability to knock the fan off with the existing 2 pole pull cord in the bathroom sounds like a good option. Though I'm still not sure of the purpose of the 3 pole isolator when I can just knock it off at the MCB.

You need a separate point of isolation to the rest of the circuit for maintenance purposes (cleaning or replacing the fan etc) you can still have the lights on when working on that part of the circuit with an isolator and the FCU will cut the line but not the neutral unless it's double pole of course