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

PeteZahut wrote:
Im looking at the possibility of buying an extractor fan with built in
spotlight like the ones used in bathrooms.
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.

Live, switched live, neutral, 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?

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

Is it just the permanent live which needs to be
fitted to this switch?

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

"Owain" wrote in message
. ..
PeteZahut wrote:
Im looking at the possibility of buying an extractor fan with built in
spotlight like the ones used in bathrooms.
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.

Live, switched live, neutral, 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?

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

Is it just the permanent live which needs to be
fitted to this switch?

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.


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

PeteZahut wrote:
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.
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,

You should also find the Permanentlive at the ceiling rose.

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

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

"Owain" wrote in message
...
PeteZahut wrote:
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.
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,

You should also find the Permanentlive at the ceiling rose.

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

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.


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
http://www.diy.com/diy/jsp/bq/produc...RODID=18 6174
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

PeteZahut wrote:
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?

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