Man rose extractor fan wiring advice

[Ksta]

Hi, please can you advise how to wire a typical manrose extractor fan with timer direct to a light switch?

I've tried various combos without success. At the moment I have:
Live from fan to live at switch (with light rose live)
Neutral from fan to L1 at switch (with light rose neutral)
Switch live from fan to L2 at switch

The result: the fan comes on when the light is switched on, and stays on!

I am expecting for the fan to start when the light I switched on, and then cut out as per the timer setting. I would even settle for the fan to switch off when the light is switched off.

Could the timer be faulty? Any advise on the wiring would be appreciate. I'm just hoping that I don't need to run a wire to the light terminal from the fan

Many thanks

 

[Lectrician]

Photo?

I doubt you have a neutral at the switch.

 

[EFLImpudence]

What terminals do you have on the switch?

Just L1 & L2,
Com, L1 & L2 or
L1, L2 & L3 ?

 

[JohnW2]

The result: the fan comes on when the light is switched on, and stays on! ... I am expecting for the fan to start when the light I switched on, and then cut out as per the timer setting. I would even settle for the fan to switch off when the light is switched off.

Quite apart from considerations of the wiring ....

With any standard timer fan (and I'm sure that's what a Manrose one would be), the intended functionality is that the fan comes on when the light is switched on, remains on all the time the light is on, and the goes off after the set time delay period after the light has been switched off.

When you say that "the fan comes on when the light is switched on, and stays on" are you sure that you are waiting long enough after the light is switched off for the fan to go off? If you have the timer adjusted for a long delay, it could be 15 minutes, possibly a fair bit longer, after the light is switched off that the fan goes off. If you turn the timer delay down to its minimum, it will be easier to test, since the fan should then go off fairly soon after the light is turned off.

Kind Regards, John

 

[PrenticeBoyofDerry]

As above the fan could well have a pre-set overrun of 15-20 mins.
The neutral would rarely be taken back to the switch and would not be at an L terminal. The normal set-up would have a fan isolator between light and fan and require to be fused at 3A.

I would expect this information to be within the manufacturers instructions.

 

[JohnW2]

The neutral would rarely be taken back to the switch and would not be at an L terminal.

Indeed - but the confusing thing is that the OP has somehow got the fan to run (including when the light is on) with the wiring he has done. If he had connected the fan (L & N) between L and S/L terminals of the switch, it certainly wouldn't work when the light was on, because there would be no voltage between the fan's L and N terminals, but the fan might possibly work with the light off (the fan having a return path to neutral through the lamp) - and all that assuming that voltage was somehow getting to the fan's trigger ('S/L') terminal. It's all rather odd.

Some photos (particularly of the switch wiring) might possibly help us to understand what is going on.

Kind Regards, John

 

[Taylortwocities]

I'm just hoping that I don't need to run a wire to the light terminal from the fan

Unfortunately, that may be the only place where you can connect up live, neutral and switched live to the fan. This will also depend on how your lights are wired.
You may need to be installing a 3-pole fan isolation switch as well…

Per the above posts, pictures needed!

 

[JohnW2]

I'm just hoping that I don't need to run a wire to the light terminal from the fan

Unfortunately, that may be the only place where you can connect up live, neutral and switched live to the fan. This will also depend on how your lights are wired.

Indeed - but, as I recently wrote, if the OP has managed to get the fan to run, when the light is switched on (hence no pd across switch terminals), this seems to imply that he must have found a neutral somewhere (and there is bound to be both a L and S/.L at the switch). As I said, I'm very confused!

Kind Regards, John

 

[DetlefSchmitz]

Dare I point out he may have found an earth?

 

[PrenticeBoyofDerry]

Dare I point out he may have found an earth?

You dare! You have! He might!

 

[Taylortwocities]

 

[JohnW2]

Dare I point out he may have found an earth?

Good point! ... even more reason to see some piccies!

Ksta: What sort of cable have you used to connect the fan to the switch?

Kind Regards, John

 

[Ksta]

Hi All, many thanks for the debate so far. To clarify:

The fan activates when the light is switched OFF.

The light switch has L1, L2, & L3.

And yes, the earth has been purposely found as there is only a 1.5 cable between fan and light switch and no other alternatives to run cables. The earth is well insulated.

 

[Taylortwocities]

To clarify:

The fan activates when the light is switched OFF.

OK, so the way you have wired it is wrong.
The fan is switching on when the switch is off because it is finding a neutral feed through the light bulb.

THERE IS NO NEUTRAL AT THE SWITCH!!!!

I know exactly where you have gone wrong but, as requested, many times above we need a photo of your wiring, no pikkie, no helpie.

 

[JohnW2]

To clarify: The fan activates when the light is switched OFF.

As TTC says, that explains everything. As both he and I have said, that means that you have wired the fan across the switch, with no neutral feed and, when the light is switched off, the fan gets a path to neutral via the lamp. You will not get it working without a neutral feed, which will probably have to come from the ceiling rose.

The light switch has L1, L2, & L3. And yes, the earth has been purposely found as there is only a 1.5 cable between fan and light switch and no other alternatives to run cables. The earth is well insulated.

Are you talking about 1.5mm 'twin & earth' cable, and that you are using the bare 'earth' conductor for one of the feeds to the fan. If so, that is definitely not acceptable, even if you have insulated the bare conductor at the ends.

Kind Regards, John