[Rob P]

Years ago I installed an extractor fan in the bathroom ceiling, venting to the outside by the simple expedient of putting a junction box in the loft within the wiring for the two lights and running a wire from junction box to fan. It has worked perfectly for twenty years, needing just one replacement fan.

When the lights were switched off the fan would run for a predetermined length of time, adjustable. The terminals on the fan were labelled L and N.

That fan died and I am replacing it with the one Screwfix had in stock.

Regrettably this has three terminals, the interloper being marked LS which I find means Switched Live. Stuffing the brown wire into either of these terminals elicits no effect. I can get the fan to run concurrent with the light by bridging L to LS. But of the timer which the fan proudly proclaims it has, there is no sign.

Help and advice needed

Rob P

[Gas Guzzler]

You need a permanent Live connection to "L" Neutral to "N" and the switched live "LS" should come from the switched live to the lights

[Rob P]

Simple when you know how, thank you. All I need to do now is figure out where I take the permanent live from.

Many thanks.

Rob P

[Gas Guzzler]

Find the cable that goes to your light switch, one wire will be permanent live the other switched live. Take care as they could be either black or red, or if later wiring could be either blue or brown or could also be grey. That's probably just complicated things but just remember electrons don't care what colour the wire is.

[Paul_Sengupta]

Simple when you know how, thank you. All I need to do now is figure out where I take the permanent live from.

How did the previous fan work after the light was turned off if there wasn't a continuous live and only a switched live?

[Rob P]

I've been wondering that too.

I am starting to think that I had better instructions twenty years back and in fact the green/yellow wire I'm currently not using is connected at the other end to a permanent live.

Rob P

[Colonel Panic]

... and in fact the green/yellow wire I'm currently not using is connected at the other end to a permanent live.

One would certainly hope not - very naughty if so.

Do you have a widget to test it (not your finger?)

[stevelup]

Yes, it very much sounds like you used the CPC (earth) as the live or switched live... Which is a massive no-no.

You either need a length of 3 core and earth cable or run an additional length of 2C+E.

[Rob P]

I told you I was an electrical dummy!

When I can summon up the will to climb into the loft again I shall check and correct. And yes I do have what we used to call an Avo back in the day, now a little plastic thing.

Rob P

[PeteSpencer]

Following with interest : the light-timer/delay-connected extractor fan in our hall khazi has just packed up and they don’t seem to sell same model any more .
Screwfix is just up the road…..

[Elecy]

Following with interest : the light-timer/delay-connected extractor fan in our hall khazi has just packed up and they don’t seem to sell same model any more .
Screwfix is just up the road…..

As your installation will be more recent you’ll probably find it’ll be a like for like replacement, hopefully even the fixing holes to screw the unit to the ceiling / wall will be in the same position.

Mark

[Rob P]

This is the one now fitted.



Rob P

[PeteSpencer]

[quote="Rob P"]This is the one now fitted.



Rob P[/quote}

As a matter of interest is it mounted direct onto joists or do you have a rubber vibration-damping mount?

I ask because our bedroom ensuite fan is in the ducting just overhead the bed and is getting noisier and I am thinking of going on a noise-damping expedition: It's the ten foot deep fibreglass insulation that has been putting me off.......

[Rob P]

Direct, but it is over the bathroom so requires no noise damping.

Rob P

[PeteSpencer]

Following with interest : the light-timer/delay-connected extractor fan in our hall khazi has just packed up and they don’t seem to sell same model any more .
Screwfix is just up the road…..

As your installation will be more recent you’ll probably find it’ll be a like for like replacement, hopefully even the fixing holes to screw the unit to the ceiling / wall will be in the same position.

Mark

Took it to bits and found circuit board fried .Fan manuf identified circuit board replacement ordered and on the way £15! Looking hopeful