wiring an Extractor Fan

Postby gselliott » Mon Apr 16, 2007 9:29 pm

I have recently bought a new (old) house and I am slowly replacing light fittings and sockets etc. I am currently trying to replace the old Extractor Fan in the bathroom that no longer works.

I have swapped the old fan with a new timer fan, it is connected to the bathroom lights (same as the old one) so when you switch the lights on (pull switch) the fan kicks in, this in itself works fine but I would like to be able to switch the extractor off seperately if i wanted to so I could have the lights on but no extractor or extractor on but no lights.

I'm not really sure how to do this, this is how it is all wired up at the mo: there are 3 cables coming out of the terminal 1 from the lighting circuit 1 going to the pull switch and 1 going to the extractor.

Is it possible to add a seperate switch for the extractor? If so where will it go?

Thanks in advance!
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Simply Build It

Postby sparx » Tue Apr 17, 2007 7:04 am

it is not only possible it is an IEE requirement that u have an isolator switch for your fan.....usual way is with a fan switch which is a 3 pole switch which breaks all lives & neutral. so you divert your 3core and earth cable from light to fan via switch just outside the room. u can buy correct sw. in B&Q etc
regards SPARX
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Postby gselliott » Tue Apr 17, 2007 8:04 am

Thanks for the reply much appreciated!

Still a bit unsure as to where i need the switch to go? at the moment the cable from the light to the fan is controlled by the light switch so i assume it wont go on there?

Sorry if i'm being stupid can't get my head around this one!

Thanks again.
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Joined: Mon Apr 16, 2007 9:07 pm

Postby sparx » Wed Apr 18, 2007 8:52 pm

OK , I just read your original post again, sorry if reply not good but if you do this work a lot it's easy to make assumptions so will try again...
your fan is connected to the light neutral & earth, it is also connected to the switched line in the light,
in order for the fan to 'run-on' after light turned off it also connects to the permanent live loop-in terminal of the light, (the bunch of 3 or 4 reds).
this lot will be in a 3core & earth cable going to the fan.
you will be able to prevent the fan operating but in order to have fan only be more difficult as will need yet onother switch...
one step at a time, at the fan note wiring colours ie R.Y.B , to which term. probably R=perm.LIVE
Y = SW. LIVE, B = NEUTRAL , plus Earth
once disconnected reroute this 3c+e to a 3pole fan sw. as I explained B4 it can be either a wall switch above the door out side room say or a fan pull sw. inside room near existing pull sw.
then run new 3c &E from sw. back to fan and connect as to original noted connections.
at new switch connect in/out cores as marked ie,
L1 in to L1 out. L2 to L2 out N-N out, earths to E term (or block),
now you can totally isolate fan when not wanted or to clean etc.
Get this working first & we'll see about other options next post, Regards SPARX
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