Wiring a timed Extractor Fan

[vaderag]

We have a bathroom extension which is essentially sealed off from the rest of the house. I am unable to find or reach the junction box which serves it - the best thing I can access is the pull switch.

I believe that I can run a non timed extractor fan from this without too much difficulty, but ideally, I'd like to install a timed fan as the bathroom does get quite damp. Without having access to the junction box, I was wondering if there is anything problematic with adding a join prior to the switch to provide the second live to the extractor fan?

Additionally - is it essential to have an isolator switch or is this just a suggestion? I can totally see the point in it, but it does make the job a bit more difficult as I don't really have anywhere to put it!!

Thanks in advance for any advice!

 

[Taylortwocities]

An isolator switch is there to provide a way of switching off all of the live connections to the fan if you need to work on it. This is essential if the bathroom has no windows.

For a timed fan to work, you will need permanent live, switched live AND neutral. Most switches will not have the neutral there, so it may not be possible to do this just from the switch, you may need to wire from teh switch (live and switched live) and from the light itself (neutral).

Can you describe (or post a photo) of the connections in the switch itself?

 

[alan333]

As mentioned above, timer fans need a permanent live, switched live and a neutral. This means running cable from your permanent source (like a junction box) and from a switch source (like a light switch or shower pull cord).

You can also get humidistat fans which will go on/off by themselves as required by moisture in the air. The pull cord ones seem to only require a permanent live and neutral to work (maybe easier for your install?) and, although they will come on when moisture is detected, they can also be switched onto timer mode by the pull cord (handy if someone's just had a jobby?). I haven't used one tho so can't comment on how effective they are. See the following link for an explanation...

http://www.fantronix.com/acatalog/Product_options_explained.html

 

[vaderag]

Thanks for the responses.

There are windows in the bathroom, so it sounds like the extra switch is not required.

I took a picture of the inside of the light switch as requested, tho not sure how useful it is - see: http://1drv.ms/1imX50i

The humidistat fans seems to be a good idea, but will need to look at the cost!!

So, if i'm understanding correctly, if possible (will need to check where the joists are to see if I can route it), I will need to take the two lives from either side of the switch, and a neutral from the light fitting itself... correct?

 

[vaderag]

One other question I had, was if i buy a timed one and I discover I can't get the neutral from the light for some reason, is it possible to wire it to act as a non-timed version?

 

[Aragorn84]

you require a neutral either way.

The light must have a neutral present or it wouldnt work.