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.