LED Lamps and extractor fan problems..

ash_s3 · Dec 5, 2014

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

Mr Brady · Dec 6, 2014

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 · Dec 6, 2014

tazz said:
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 · Dec 6, 2014

Look at this...

[ElectriciansForums.net] LED Lamps and extractor fan problems..

HandySparks · Dec 6, 2014

uksparks said:
Look at this...

Your point being..?

davesparks · Dec 6, 2014

+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 · Dec 6, 2014

davesparks said:
+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 · Dec 6, 2014

HandySparks said:
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 · Dec 6, 2014

uksparks said:
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 · Dec 6, 2014

uksparks said:
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 · Dec 6, 2014

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 · Dec 7, 2014

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 · Dec 7, 2014

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 · Dec 7, 2014

uksparks said:
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 · Dec 7, 2014

uksparks said:
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.