Extractor fan with light

[PeteZahut]

Im looking at the possibility of buying an extractor fan with built in spotlight like the ones used in bathrooms. The reason for this is to help in cooling down the computer room. What Im proposing doing is fitting this and running the outlet pipe???? through the eaves. I know we can just leave a window open but the problem with this is moths etc coming in of a night time and the wife wont entertain one of those fly screens across the window. If we had a fan in the ceiling we would have an airflow there because the hall has a few airbricks which are very efficient. Im thinking this would work, any ideas? Secondly, the ones I have been looking at require 4 wires and an isolating switch. The four wires are one permanent live to enable the fan to run on when the light goes off. One live, one neutral (switched live?) and one earth. I gather the isolating switch is to enable work to be carried out on the fan if needed but how would this be done. Dont all isolating switches only have three connection points? Is it just the permanent live which needs to be fitted to this switch? I hope Ive explained that well enough. Cheers Pete

[Owain]

Live, switched live, neutral, earth.

Fan isolators have three poles (L, SL, N - the earth is *never* switched).

Assuming you don't want to use the timer facility, supply the fan with Live and Neutral, and link the PermanentLive and SwitchedLive terminals at the fan. If you are taking the supply from a socket circuit, use a Fused Connection Unit fused at 3A.

Owain

[PeteZahut]

Thanks so far Owain, what i was hoping to do was just replace the pendant light which is in the computer room, this would give me a switched live, neutral and earth, I was then going to take the permanent live from the feed to the lights and use a shower type pull cord switch or just one of the wall type shower/cooker switches which would be out of sight but accessible if needed, but also left on . Could i do this, I'd then have my twin and earth and strap a red wire to this. If I can do it that way, how would I wire the pull cord switch? Would i be wrong in thinking that just having a switch to isolate the permanent live will be ok, the lights obviously are covered by the consumer unit. I would want the fan to run after the light has been turned off. Pete

[Owain]

You should also find the Permanentlive at the ceiling rose.

If you want the fan to run on after the light (on the timer), you will need separate Permanentlive and Switchedlive to the fan, in parallel with the connections at the ceiling rose, going through a 3pole isolator ot the fan.

*All* poles (including Neutral) to the fan must have an isolation switch.

Owain

[PeteZahut]

Ok thanks again but I think my wording may not be very good in this one. The fan/light fitting is all in one, it has a light in the centre and an extractor on the outside of it. Its very similar to this one

but I have found it cheaper in a local diy shop which is closing down. The fitting has a connection box away from the light/fan but only has four connections. Sort of like a ceiling rose has the connections then a length of wire to the pendant. In the light/fan fitting there is the junction box then a pre-fitted wire to the actual light/fan (not two seperate feeds). Unfortunately because its been on display in the shop there are no instructions. However, the man behind the counter has said you could use the brown, blue and earth wires from the pendant and add a red wire for the permanent live . I know I can take all these from the ceiling rose as it is but I'd like to be able to isolate the permanent live just in case plus keep the original light switch, hence the out of reach switch. Does that make sense or is it overkill on the safety side? Pete

[Owain]

Then you need to take a triple-and-earth from the existing (ceiling rose as is) terminals to a 3-pole isolator, then back to the fan/light. This will be easier if you can open a trap above the ceiling rose and pull the cables (*label them first*) back into the ceiling void and fit a junction box.

You can mount the fan isolator switch on the ceiling if you want.

This will leave the original light switch controlling the light/fan, with timer overun of the fan.

Owain