LED Lamps and extractor fan problems..

[ash_s3]

A friend of mine has just replaced some halogen GU10 lamps in his bathroom with LED lamps from Amazon.

Hes saying since swapping the lamps, the extractor fan runs continuously. (230v in-line unit in the loft with over run timer)

He tried swapping one LED lamp back to halogen and it worked as it should, timing out after 5mins or so.

Removed the halogen (with the lights switched off) and the fan fired up by itself!

Anyone come across this before? Sounds like a resistance issue to me, would a resistor sort this out?

Cheers

 

[uksparks]

Hi,

Sounds like something is wired wrong or badly connected as the fan switching is nothing to do with that of the actual lamp holder or the load connected to it IMHO.

 

[uksparks]

just to add, I have fitted a significant number of LED GU10's and extractors together and never once had a problem.

 

[ash_s3]

Thanks bud, il take a look over the weekend. Certainly does sound odd

 

[ash_s3]

I was thinking could the LEDs be holding a small voltage, enough to trigger the switched live of the fan?

 

[uksparks]

I was thinking something like that but then I thought well no, if it's wired correctly and your switch works as it should then the switch should physically cut it off.

 

[ash_s3]

Yes I see what your saying, I was thinking of some kind of capacitance in the lamps themselves? Once switched off, still holding a small charge.
I could be talking nonsense but just wanted to see if anyone else had any clues before I go take a look! Thanks

 

[HandySparks]

You've got a small amount of capacitive or inductive coupling from a permanent live to the switched live powering the lights (and fan trigger).

With at least one halogen lamp fitted, its relatively low resistance is enough to reduce the phantom voltage to a negligibly low value, so the fan switches off as normal. If you only have LED lamps fitted, they will have a fairly high impedance non-resistive loading on the switched line, which will allow the phantom voltage to rise to sufficient level to trigger the fan. Adding a well chosen resistor across the switched line and neutral will sort the problem. A low wattage filament lamp would do (as you have found) although a much higher resistance will do the job. The resistance value required will have to be found by experiment and the resistor wattage chosen to suit.

Alternatively, some re-routing of the cables may do the job. May require separating the switched live from the permanent live.

 

[ash_s3]

Thank you, so the voltage could be inducing inside the 3C+E to the fan?
Similar sort of problem to the dimly glowing LEDs on 2way switches then.

 

[HandySparks]

Thank you, so the voltage could be inducing inside the 3C+E to the fan?
Similar sort of problem to the dimly glowing LEDs on 2way switches then.

Exactly. That's what I'm surmising, anyway. Not experienced this problem personally.

 

[dmacab]

We have had same issue with central extract systems çonstantly boosting due to some sort of issue with a small voltage at switched live. This is interesting.

 

[tazz]

If the fan is coming on when switch is off, then the fan is wired incorrectly...nothing to do with lighting.

 

[ash_s3]

If the fan is coming on when switch is off, then the fan is wired incorrectly...nothing to do with lighting.

The fan has been working fine for 18months with halogen lamps in the bathroom, can't be wired incorrectly in my opinion mate.

 

[Mr Brady]

Hi, another solution if the circumstances suit it, would be to wire a 3core+e to the switch then change the switch to a DP one, giving each "switched live" it's own pole which are electrically separated when the switch is off.

 

[Octopus]

Hi, another solution if the circumstances suit it, would be to wire a 3core+e to the switch then change the switch to a DP one, giving each "switched live" it's own pole which are electrically separated when the switch is off.

Not ideal with an over run timer!

 

[Mr Brady]

Hi, what I mean't was, one switched live to the lights, one to the fan, which would of course still have it's permanent live.
So the fan no longer picks up it's switched live from the lights but is connected through to it's own pole of the switch.

 

[uksparks]

If the fan is coming on when switch is off, then the fan is wired incorrectly...nothing to do with lighting.

My thoughts entirely

 

[uksparks]

Look at this...

 

[HandySparks]

Look at this...

Your point being..?

 

[davesparks]

+1 for capacitive coupling.

If it all works fine with gu10s then misbehaves with LEDs fitted then I don't see how it can be connected incorrectly.

 

[uksparks]

+1 for capacitive coupling.

If it all works fine with gu10s then misbehaves with LEDs fitted then I don't see how it can be connected incorrectly.

How much voltage are we talking about here?

Also, when you say it turns the fan on, if it was only a capacitive thing, then surely it will run out this making the fan switch off on the end of its timer run?

 

[uksparks]

Your point being..?

Just saying really, didn't have any comment on it, just for the lesser educated on how its connected thats all, more information than anything.

 

[HandySparks]

How much voltage are we talking about here?

Also, when you say it turns the fan on, if it was only a capacitive thing, then surely it will run out this making the fan switch off on the end of its timer run?

We're not talking about DC filling up a cap which then triggers the fan. The capacitive coupling is AC, providing a weak link between the perm live and switched live; it's a continuous process, so 'running out' doesn't come into it.

No idea of the voltages involved. The voltage required to trigger the fan and the input impedance will vary from one model to the next.

 

[ash_s3]

Just saying really, didn't have any comment on it, just for the lesser educated on how its connected thats all, more information than anything.

This is how I see it.
The permanent live is always at the fan, this permanent live is inducing a voltage in the switched live of the 3c&e, the LED lamps won't illuminate with such small voltage so the voltage stays in the conductor.
With halogens, the voltage is dropped through the filament?
i take it that with these timer fans, the motor runs off the perm live and the switched live is just a trigger to start the timer? So even a small voltage could trigger it?

 

[tazz]

Then the SWL and L to the fan must be wired incorrectly with the lighting circuit.....by removing the halogens which you state brings on the fan, whilst switch off. I would Ask where is the fan getting the SWL voltage from..?

 

[uksparks]

I'm sticking with the theory of its wired incorrectly. I don't buy the inductance thing, we are talking about a bathroom light not a supermarket full of lights.

It's been poorly wired and incorrectly too and we have not been told the full picture like I've frigged around with it and don't know what I'm doing....

 

[ImpededLoop]

Not experienced this myself, but if it is wired correctly, you could install a relay next to the fan or the isolator to disconnect the SL from the lamps when the switch is off.

 

[davesparks]

How much voltage are we talking about here?

Also, when you say it turns the fan on, if it was only a capacitive thing, then surely it will run out this making the fan switch off on the end of its timer run?

How can capacitive coupling run out?

If the trigger for the fan is over sensitive then it could take next to nothing to trigger it.

 

[davesparks]

I'm sticking with the theory of its wired incorrectly. I don't buy the inductance thing, we are talking about a bathroom light not a supermarket full of lights.

It's been poorly wired and incorrectly too and we have not been told the full picture like I've frigged around with it and don't know what I'm doing....

You're mixing inductance and capacitance up, they are two different things.

Capacitive coupling is the effect which caused CFLs to flash and LEDs to glow/flash when installed on some 2 way switched circuits.

In what way are you suggesting it has been wired incorrectly? Can you describe the wiring method you think will cause this bizarre behaviour? I am curious as I cannot think of any way of connecting this which will cause he behaviour described.

 

[uksparks]

I can't think what it could be but I bet your bottom dollar that there's more to this than is made out.

 

[davesparks]

I can't think what it could be but I bet your bottom dollar that there's more to this than is made out.

If you can't come up with a way of connecting this that will cause the problem then why state that the problem is with the way if is connected ?

Random speculation doesn't help anyone.

 

[i=p/u]

short between live conductors when bird sits on roof.....

 

[ash_s3]

It's wired correctly as I installed it about 18 months ago.
Hager J804 in the loft, feed in, twin to pull cord, twin to spotlights and a 3c&e to TP fan isolator then onto the fan.
Fan is a Manrose MF100T, wiring hasn't been interfered with in the meantime.

 

[topquark]

Substitute the switch (or check the resistance across contacts in off position if you don't have a spare on you).

 

[Silly Sausage]

It's wired correctly as I installed it about 18 months ago.
Hager J804 in the loft, feed in, twin to pull cord, twin to spotlights and a 3c&e to TP fan isolator then onto the fan.
Fan is a Manrose MF100T, wiring hasn't been interfered with in the meantime.

Wire it with the Line and S/L on the outer cores, N in the middle.

 

[uksparks]

If you can't come up with a way of connecting this that will cause the problem then why state that the problem is with the way if is connected ?

Random speculation doesn't help anyone.

Sorry master Dave

 

[ash_s3]

Archy- You think it's picking up the voltage for the contacts inside the isolator?

 

[Silly Sausage]

Archy- You think it's picking up the voltage for the contacts inside the isolator?

Sorry, a bit vague there, I mean the cable.
May as well do the same at the isolator.

If it isn't already wired this way, give it a try and let us know the result...put us all out of our misery! :smilielol5:

 

[HandySparks]

Wire it with the Line and S/L on the outer cores, N in the middle.

Yep, worth a try.

 

[ash_s3]

Sorry chaps I'm not really following here.

Connecting the Line and S-Line opposite ends of the isolator - is this to keep the cores apart in the pattress?

 

[davesparks]

Sorry chaps I'm not really following here.

Connecting the Line and S-Line opposite ends of the isolator - is this to keep the cores apart in the pattress?

In the cable!

Do you understand how capacitive coupling works?
There are many threads on here discussing if if you search.

 

[ash_s3]

Ah I see now, so the N and E are in between the two Lines of the cable.

And no I'm not clued up on capacitive coupling, just youtube'd it and nearly slipped into a coma listening to the guy!

 

[davesparks]

Then read up on it and understand it before you go any further.

Then you can diagnose whether or not this is the problem and design a suitable soloution.

 

[ash_s3]

Will do Dave, thanks for your input.

 

[HandySparks]

Ah I see now, so the N and E are in between the two Lines of the cable.

Exactly. The permanent live will then tend to induce a little current in the N and the E (which you don't care about) rather than the switched L, which is further away on the other side of the cable.

 

[davesparks]

Exactly. The permanent live will then tend to induce a little current in the N and the E (which you don't care about) rather than the switched L, which is further away on the other side of the cable.

It won't induce, the phenomenon is capacitive not inductive

 

[HandySparks]

It won't induce, the phenomenon is capacitive not inductive

I'm using the term in its general sense, "Bring about or give rise to". What's the concise term for "to cause a current to flow due to capacitive coupling"?

 

[davesparks]

I'm using the term in its general sense, "Bring about or give rise to". What's the concise term for "to cause a current to flow due to capacitive coupling"?

When discussing electricity the word induce has a specific meaning, using it otherwise is only going to give rise to confusion.

I doubt there is a concise term, we are talking about a technical/scientific subject which is something that doesn't work well with shortening terms down for convenience

 

[Silly Sausage]

I'm using the term in its general sense, "Bring about or give rise to". What's the concise term for "to cause a current to flow due to capacitive coupling"?

I think in these cases, it's just a case of the circuit acting as a capacitor connected across an AC voltage source.
So it's just the 'natural' (high end terminology there!!!) current flow, in these cases in the order of micro Amps.
Which are starting to have a/or producing, odd effects on newer low power gear.

 

[Octopus]

This may, or maynot be helpful but....

Today I investigated a bathroom where the lights (LED's) stayed on when the lights were off!

So I removed the cover of the ceiling mounted fan...... and narrowly avoided being "drenched" by the build up of water (condensation) that had accumulated and clearly the moisture was providing the "connection" between the SL and L.

With the fan cover off, and the fan disconnected, the lights now work perfectly.

Hope this is of use to some of you!