Hi all,
I bought an extractor fan and have since build it into the wall and
now I must wire it up to the light. Is there any pitfalls/ advice to
look out for? It's the type that comes on when the light is switched
on.

Thanks

igloo wrote:
Hi all,
I bought an extractor fan and have since build it into the wall and
now I must wire it up to the light. Is there any pitfalls/ advice to
look out for? It's the type that comes on when the light is switched
on.

Thanks

It will need a 4 core cable. Earth, live, switched-live and neutral wired to
the ceiling rose.
Strictly speaking you should wire it through a double pole fused connection
unit but many people do not seem to bother with this...

BillR scribbled :
It will need a 4 core cable. Earth, live, switched-live and neutral
wired to the ceiling rose.
Strictly speaking you should wire it through a double pole fused
connection unit but many people do not seem to bother with this...

I always use a triple pole switch which is specifically for fans.
You need to isolate the L, N and SL.
If you use a double pole fused connection unit then the outgoing load should
also feed the light in the same room as the fan so when you isolate it the
light cannot be switched on causing the Switched Live to become live at the
fan.

--
Gary
Please remove #NOSPAM# if replying via email

Gary wrote:
BillR scribbled :
It will need a 4 core cable. Earth, live, switched-live and neutral
wired to the ceiling rose.
Strictly speaking you should wire it through a double pole fused
connection unit but many people do not seem to bother with this...

I always use a triple pole switch which is specifically for fans.
You need to isolate the L, N and SL.
If you use a double pole fused connection unit then the outgoing load
should also feed the light in the same room as the fan so when you
isolate it the light cannot be switched on causing the Switched Live
to become live at the fan.

You're right, it should be a triple pole switch. Big ugly things they are
too and they don't seem to match normal light switches...

"BillR" wrote in message
...
igloo wrote:
Hi all,
I bought an extractor fan and have since build it into the wall and
now I must wire it up to the light. Is there any pitfalls/ advice to
look out for? It's the type that comes on when the light is switched
on.

Thanks

It will need a 4 core cable. Earth, live, switched-live and neutral wired
to
the ceiling rose.
Strictly speaking you should wire it through a double pole fused
connection
unit but many people do not seem to bother with this...

The fan will only require 4 core (1mm2 3 core and earth) if the fan is a
timer over run version. Use 3 core (or 2 core 1mm2 T&E if it has no timer
overrun)The cable should pass through a triple pole isolator to do this
properly on a timer overrun version. If the fan has no timer then the cable
may go through a double pole switch or double pole fused connection unit

--
Adam

BillR wrote:

Gary wrote:

BillR scribbled :

It will need a 4 core cable. Earth, live, switched-live and neutral
wired to the ceiling rose.
Strictly speaking you should wire it through a double pole fused
connection unit but many people do not seem to bother with this...

I always use a triple pole switch which is specifically for fans.
You need to isolate the L, N and SL.
If you use a double pole fused connection unit then the outgoing load
should also feed the light in the same room as the fan so when you
isolate it the light cannot be switched on causing the Switched Live
to become live at the fan.


You're right, it should be a triple pole switch. Big ugly things they are
too and they don't seem to match normal light switches...




Oh? I found nice brass ones with fuses that EXACtLY match the light
switches.

In article ,
"BillR" writes:

You're right, it should be a triple pole switch. Big ugly things they are
too and they don't seem to match normal light switches...

They're usually a triple light switch, but with a large rocker
jammed onto all the actuators.

--
Andrew Gabriel

Andrew Gabriel scribbled :
They're usually a triple light switch, but with a large rocker
jammed onto all the actuators.

And normally mounted at high level so an exact match with a light switch
will not become an issue.
--
Gary
Please remove #NOSPAM# if replying via email

Gulp. I'll get an electrician!

"Gary" wrote in message
...
Andrew Gabriel scribbled :
They're usually a triple light switch, but with a large rocker
jammed onto all the actuators.

And normally mounted at high level so an exact match with a light switch
will not become an issue.
--
Gary
Please remove #NOSPAM# if replying via email



I been on few new housing estates round my area and noticed how these
installations had been done on new builds.

The light switch and TP fan isolator were mounted adjacent to each other
outside the bathroom/ensuite. Some estates also included a 3 amp FCU
adjacent to these. If the FCU was fitted, the bathroom light and fan were
all wired behind the 3 amp fuse. (The FCU should be fitted if the fan
manufactuter's instructions call for it).

Disadvantages of wiring the fan to the light are...
You always have to operate the light to get the fan to run, even during the
day.
At night you always put the light on, so the fan runs, whether you need it
to or not.

Mounting the TP isolator in a convenient position gives the option of
silencing the fan if it is not required.

BillP.

The Natural Philosopher wrote:
BillR wrote:

Gary wrote:

BillR scribbled :

It will need a 4 core cable. Earth, live, switched-live and neutral
wired to the ceiling rose.
Strictly speaking you should wire it through a double pole fused
connection unit but many people do not seem to bother with this...

I always use a triple pole switch which is specifically for fans.
You need to isolate the L, N and SL.
If you use a double pole fused connection unit then the outgoing
load should also feed the light in the same room as the fan so when
you isolate it the light cannot be switched on causing the Switched
Live
to become live at the fan.


You're right, it should be a triple pole switch. Big ugly things
they are too and they don't seem to match normal light switches...




Oh? I found nice brass ones with fuses that EXACtLY match the light
switches.

Fine if you've got brass light switches...

"igloo" wrote
| Gulp. I'll get an electrician!

No, you get (assuming it's a timer over run fan) a length of
triple-and-earth cable and a triple-pole fan isolator switch (which are
readily available in the sheds). (Switch off at the mains first, usual
disclaimers etc.)

Take the cable from the light to the isolator switch location and then from
the switch to the fan. The switch needs to be out of reach of the bath or
shower - google Bathroom Zones for more info.

At the light, terminate red on the Permanent Live (this will probably
already have 3 reds on it, 2 for the lighting loop and 1 for the switch
feed). Terminate yellow on the Switched Live (this may be a single red for
the switch return, or a black with a red sleeve, or just a black, but will
connect to one side of the bulb). Treminate the blue on the Neutral (this
will probably already have 2 blacks on it for the lighting loop, and connect
to the other side of the bulb).

At the switch, just match up the red yellow blue on the supply side of the
switch to red yellow blue on the load side.

At the fan, terminate red on L, blue on N, and yellow on the teminal
probably marked Trigger.

All earths need green/yellow sleeving and to be connected up even if the fan
is double insulated.

Owain