Shower room extractor fan - Part 2 (the saga continues after a new fan is installed)

[Rollerball]

Thought it best to make a new thread given that some of the circumstances have changed, this new thread continues on from the following:

Shower room extractor fan - used to turn on and off via the light switch, but now ........

The light switch outside the small shower room also turns on the extractor fan on the shower room ceiling. Or rather it used to, now when I turn on the light switch the light comes on but not the fan, to then turn on the fan I need to stand on a stepladder and pull the pull cord attachment on...

www.diynot.com

So I installed a replacement fan - the original was a Greenvac Airvac AX100T, I bought what is advertised as a direct replacement, the AXS100T

Do bear in mind that the original AX100T used to switch on via the light switch, so the AXS100T, as a direct replacement, should also do the same ...... yet it doesn't. It DOES switch on via the pull cord (the original also had a pull cord switch which worked), and prior to that when I flip the light switch the new fan does briefly turn but then stops.

There is a fan, the AXS100, which is NOT stated as being a direct replacement for the AX100T (it's instead a replacement for the NDX100B). but that one IS advertised as "Remotely Switched".

Also bear in mind that the lights in the shower room are three small 12 volt spot bulbs with a converter of some sort in the attic.

So I'm puzzled - I can't work out how the original fan worked just fine from the light switch and then stopped doing so a few years ago. And also, even though it's not advertised as being a 'remotely switched' fan, why the 'direct replacement' won't work in the same way.

Note that the electrical terminals inside the original fan are marked L, N and SL (there's the stub of a wire in the SL terminal and in the electrical cable (Red, Black and a bare wire for Earth) the bare Earth wire is just a stub and it's a lot shorter than the Live and Neutral wires).

Is it possible that the unused Earth was wired as some kind of Switched Live ? Surely not? If so, perhaps it corroded and broke off?) I didn't see any piece of spare wire though).

The terminals inside the replacement are L, N and L1. I've not used L1.

The instructions for the replacement (which also cover other models in the range) are available in the Downloads area of the following page of the manufacturer's web site:

Select 100 | Greenwood

www.greenwood.co.uk

I'm also now wondering if all of this is safe. It's been wired this way for over twenty years. Perhaps it's time to find a local electrician to take a look?

 

[EFLImpudence]

The terminals inside the replacement are L, N and L1. I've not used L1.

Then it won't work.

If you only have two wires, red and black, then the red needs to be connected to both L and L1 but the timer won't work.

Perhaps it's time to find a local electrician to take a look?

Definitely.

 

[Wayners]

L is permanent live. Never goes off unless you have a isolation switch. This powers the fan after the bathroom light is switched off.

L1 is the switch wire. This lets the fan know when you turn light on and off.

N is neutral

Earth is earth.

So you need both the permanent live ( on 24/7) and a pull switch live.

I bought a timer fan with a pull cord on side as cheaper than standard fan at the time. i just bypassed it all. Fan comes on and off with light switch. That's it

 

[Rollerball]

Thanks both of you, it sounds simple enough to wire L to L1 so I'm tempted to give that a try, but also perhaps contact an electrician to look into it all just to check the wiring for that part of the circuit.

I guess that as it's wired right now it's perfectly safe in the sense that I've simply connected up the new fan the same way as the old fan?

 

[JohnW2]

Note that the electrical terminals inside the original fan are marked L, N and SL (there's the stub of a wire in the SL terminal and in the electrical cable (Red, Black and a bare wire for Earth) the bare Earth wire is just a stub and it's a lot shorter than the Live and Neutral wires).

Can you explain a it more about these 'stubs'. The fan would never have come on with the lights if there was not a connection (from the light) to the SL terminal of the fan, so ...

Is it possible that the unused Earth was wired as some kind of Switched Live ? Surely not?

Despite your "Surely not?", it's certainnly far from unknown - and if that is what had been done, as you go on to say...

If so, perhaps it corroded and broke off?) I didn't see any piece of spare wire though).

The terminals inside the replacement are L, N and L1. I've not used L1.

That L1 is presumably the equivalent of the 'SL' on the original one - and, as has been said, if you've not connected anything to L1, the fan could not come on with the light.

 

[JohnW2]

If you only have two wires, red and black, then the red needs to be connected to both L and L1 but the timer won't work.

What would happen if the red were connected to both L and L1 would presumably depend on what that red wire was (i.e. where it came from). If (as I presume you are assuming) it was the 'switched live' from the light then, as you say, the fan would come on whenever the light was on, but would go off immediately when the light was turned off (no 'timed run-on').

However, if it (the red wire) were a 'permanent live', then the fan would potentially be on continuously (regardless of whether light was on), although the fan's pull switch might well then enable it to be switched off (I need to look at the fan's documentation to see).

As has been implied, if the only cable is one with just a red, black and bare 'earth' then, if the fan ever worked 'as expected' with the light, then it seems inevitable that the CPC (bare 'earth wire') of the cable was then being used for the switched live - but that obviously doesn't explain what resulted in that seemingly becoming 'disconnected'.

 

[Rollerball]

Can you explain a it more about these 'stubs'. The fan would never have come on with the lights if there was not a connection (from the light) to the SL terminal of the fan, so ...

Despite your "Surely not?", it's certainnly far from unknown - and if that is what had been done, as you go on to say...



That L1 is presumably the equivalent of the 'SL' on the original one - and, as has been said, if you've not connected anything to L1, the fan could not come on with the light.

There was a very short stub of wire left in the SL screw terminal in the original fan - the stub is so short that it can barely be seen.

As the live wire goes into L on the new fan and L1 has no wire, if I bridge L and L1 in the new fan is there any risk of anything going wrong - blowing a fuse for example or causing some overheating in the wiring perhaps?

If the red wire was a 'permanent live' then as you say the fan would be on continuously, but it's not.

I do wonder why, when the light switch is flicked on, the fan briefly turns.

 

[EFLImpudence]

What would happen if the red were connected to both L and L1 would presumably depend on what that red wire was (i.e. where it came from). If (as I presume you are assuming) it was the 'switched live' from the light then, as you say, the fan would come on whenever the light was on, but would go off immediately when the light was turned off (no 'timed run-on').

Yes.

However, if it (the red wire) were a 'permanent live', then the fan would potentially be on continuously (regardless of whether light was on),

Yes.

although the fan's pull switch might well then enable it to be switched off (I need to look at the fan's documentation to see).

Possibly.

I assumed the OP might tell us what the fan did when connected as I said.
Then we would know.

As has been implied, if the only cable is one with just a red, black and bare 'earth' then, if the fan ever worked 'as expected' with the light, then it seems inevitable that the CPC (bare 'earth wire') of the cable was then being used for the switched live - but that obviously doesn't explain what resulted in that seemingly becoming 'disconnected'.

Possibly at sone time - but not lately by the sound of it.

Note that the electrical terminals inside the original fan are marked L, N and SL (there's the stub of a wire in the SL terminal and in the electrical cable (Red, Black and a bare wire for Earth) the bare Earth wire is just a stub and it's a lot shorter than the Live and Neutral wires).

 

[JohnW2]

There was a very short stub of wire left in the SL screw terminal in the original fan - the stub is so short that it can barely be seen.

OK.

As the live wire goes into L on the new fan and L1 has no wire, if I bridge L and L1 in the new fan is there any risk of anything going wrong - blowing a fuse for example or causing some overheating in the wiring perhaps?

No, no risk provided you do just as was mentioned. Do not connect the back wire or N terminal to anything else, because that would result in problems

If the red wire was a 'permanent live' then as you say the fan would be on continuously, but it's not.

Only if the red wire was connected to L1 as well as L. If it were only connected to L (or only to L1, come to that), the fan could never come on with the light.

As for the circumstances (connections) that would allow the fan to come on when the pull cord was pulled, I'm still not clear as to what the functionality of the pull switch is meant to be, and none of the documentation I've looked at seems to tell me. Is there some 'user guide' or suchlike (as district from the 'installation instructions')?

I do wonder why, when the light switch is flicked on, the fan briefly turns.

That seems extremely odd, and I continue to scratch my head about that

 

[JohnW2]

Possibly at sone time - but not lately by the sound of it.

The OP seems to have told us that it (and the timer functionality) did once work (with the light), albeit a long time ago, and if the only cable is a T+E (and given that it's a timer fan) I can't see how that could ever have been the case unless the CPC were used as a S/L. Can you think of any alternative possibility?

 

[Rollerball]

OK.

No, no risk provided you do just as was mentioned. Do not connect the back wire or N terminal to anything else, because that would result in problems

I think I may have done that on my first wiring attempt - I read the 'L1' incorrectly (didn't have my glasses on) and put the black wire into L1 and the red into L. Thankfully nothing bad happened.

Only if the red wire was connected to L1 as well as L. If it were only connected to L (or only to L1, come to that), the fan could never come on with the light.

Thanks. If time allows tomorrow I'll try bridging L and L1 and report back.

As for the circumstances (connections) that would allow the fan to come on when the pull cord was pulled, I'm still not clear as to what the functionality of the pull switch is meant to be, and none of the documentation I've looked at seems to tell me. Is there some 'user guide' or suchlike (as district from the 'installation instructions')?

Unfortunately I can't seem to find any kind of user guide or similar, only the installation instructions.

That seems extremely odd, and I continue to scratch my head about that

Join the club.

 

[Rollerball]

The OP seems to have told us that it (and the timer functionality) did once work (with the light), albeit a long time ago, and if the only cable is a T+E (and given that it's a timer fan) I can't see how that could ever have been the case unless the CPC were used as a S/L. Can you think of any alternative possibility?

On the other hand my wife thinks that when the original fan used to be turning on okay via the light switch it was also immediately turning off via the light switch (so no timer operation). She could well be correct ......... (she used the shower room a lot more than me, I've always preferred to use the bath).

 

[JohnW2]

On the other hand my wife thinks that when the original fan used to be turning on okay via the light switch it was also immediately turning off via the light switch (so no timer operation). She could well be correct .........

Ok. If that was the case, then that would have been what would have happened if the red were the switched live from the light and it was connected to both L and SL of the fan.

 

[JohnW2]

I think I may have done that on my first wiring attempt - I read the 'L1' incorrectly (didn't have my glasses on) and put the black wire into L1 and the red into L. Thankfully nothing bad happened.

Getting the red and black wires 'round the wrong way' is that fashion should not do any harm.

Thanks. If time allows tomorrow I'll try bridging L and L1 and report back.

That will be interesting!

Unfortunately I can't seem to find any kind of user guide or similar, only the installation instructions.

As I implied, I had the same problem - so I remain uncertain of what that pullcord switch is meant to do.

Kind Regards, John

 

[Rollerball]

Prior to me bridging L and L1 I've been looking at the wiring diagrams for the new fan (AXS100T). It's interesting to note that the other fan (the Remotely Switched AXS100, which I don't have), if wired up with double pole isolating switch, needs a fuse on the live connection.

However with the fan that I have, if using a triple pole isolating switch, no fuse is required.

I don't know what type of light switch mine is.

Here's the two relevant wiring diagrams from the fan's installation instructions: