seperate switch and FCU for bathroom fan

[mbrxjepp]

I know I'm taking a risk here with a bathroom fan question, but i really have trawled the archives and read the faqs.

I understand previous posts, and have spoken to an electrician, about using 3core and earth via a 3 pole switch, but here's the thing...

I want to run a timed bathroom extractor fan off my lighting circuit, operated by its own switch, NOT the lightswitch. I would like to include a 3 pole isolator in the circuit. I know I can get lights and no fan with above set up by isolating the fan, but what i'm really after is fan and no lights

1. Am I right in thinking that I would have to run such a set up from a junction box added into the lighting circuit, with a 3 core and earth spur going to fan via 3 pole switch and switched live controlled by standard lightswitch? If I run from an existing ceiling rose, I assume that means my switched live will always be controlled via the lightswitch...

2. If the above is correct, how would I incorporate a double pole FCU? I have read this isn't needed, but now i'm curious more than anything, and would like the option of complying with manufacturers instructions.

Fan was from screwfix with no wiring diagram at all.

I know I might be dredging up old material here, but the archives didn't resolve my question after much searching.

Cheers,

Ewan

2.

 

[sparkyspike]

If you're running off the lighting circuit you won't need a DP FCU. Just use the 3P switch. So if you want no light control, put a DP switch in instead, you won't need a fuse.

 

[ayen]

so if i have read it correct you are picking a live feed off your bathroom light and want a separate pull cord for the fan.
If thats what you mean you should still install a 3p iso. Take twin and earth from light fitting picking up permenant live neutral and earth then make a jb with this cable a switch twin and earth from the fan pull cord and then three core and earth. Then three core to iso then fan
The iso is installed so you can isolate the fan completely.

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just read the post back hope you get the jest of what i was saying its be a long hard day

 

[breezer]

use the drawing in the sticky.

where the ligt is will be your supply, and the light switch will be your fan switch, but you will have to wire it to the fan not the light

 

[Spark123]

It might also be advisable to fit a pullcord switch with a neon indicator (requires a neutral) so you can see when the pullcord is operated.
Also, please note that this work is notifiable to LABC under part P of the building regs.

 

[ayen]

the sound of the fan normally gives it away

 

[Spark123]

Maybe, but he is wanting a timed version. Normally the light serves as an indication the switched supply is on. Unless he is gonna guess what state the switch is in, wait half an hour (or whatever the timer is set to) to see if it turns off and if it doesn't, try again!

 

[mbrxjepp]

so if i have read it correct you are picking a live feed off your bathroom light and want a separate pull cord for the fan.
If thats what you mean you should still install a 3p iso. Take twin and earth from light fitting picking up permenant live neutral and earth then make a jb with this cable a switch twin and earth from the fan pull cord and then three core and earth. Then three core to iso then fan
The iso is installed so you can isolate the fan completely.

Yeah, this is what i'm attempting, though i'm actually going to be splicing into the lighting main rather than taking a spur off the light as in my case this is easier.

Not sure if i'll use a pull cord or a wall mount switch - if I use a pull cord then an led sounds like a good idea.

Breezer, not sure if I understand how to wire the switch to the fan - I assumed I would do as mentioned above and use two core and earth to wire switch to jb.

Cheers everyone, sounds like i'm on the right track now.

Ewan