Advice on LED inductive voltage preventing LEDs switching off

[Stagbeetle]

Hi,

I'm looking for some advice on LEDs that glow when switched off in a multi-switch circuit.

Last month I replaced our old CFL lamps with multiple LED G9 'chandeliers'. The living room has a dimmer switch and the 20-odd LEDs all work fine.

However the hallway has 3 ceiling fixtures, with about 20 G9 LEDs, and 3 switches - one upstairs and 2 downstairs. They have the same LEDs as the living room but they won't stop glowing -when they are switched off they are almost as bright as when switched on.

Switching the RCD off switches the LEDs off.

My googling leads me to believe that the 40V I can see between live/neutral on the ceiling fixture, when off, is inductive voltage/capacitive coupling. I did buy a "0.1uF + 100 Ohm 250VAC triac snubber" from ebay but it didn't seem to have any effect, and the only other capacitor/resistor I found on my browsing linked to a maplin product.

I had one halogen G9 lying around which I put in the place of a single LED and it, too, glowed weakly as the LEDs shone brightly.

And that's how I've left it for a month but as June 21st has come and gone I need to sort this out. I have learned about as much as I can and am still no closer to a recognised solution.

What can I do to pin this down?

Thanks,

 

[Deleted account]

This is a bit of a pain in the a**e to be honest. I've looked into this as I've had similar issues.

I did find one solution. And that was to try a different led make.

I replaced nine 2.5watt gu9 bulbs with another nine 2.5watt gu9 bulbs of a different make. The glow no longer occurred. I don't know why.

 

[Stagbeetle]

Thanks - that would be better than keeping the RCD off! Do you remember the brand or type and I'll check to see if they have a trigger voltage or some other keyword that may help...

 

[static zap]

The glow no longer occurred. I don't know why.

..Probably every one of "Fancy" bulbs has a snubber network , in effect connected to Neutral !
( Would be interesting to put a similar bank of each on kit capable of measuring Power factor )

 

[Taylortwocities]

I have found that putting a C/R network (aka 'snubber') across the problem lamp(s) can be effective. You may get away with just one, or you may need more than one.

I used to get mine from MAPLIN (RIP).

RS Components would be a good source or (if you are prepared to risk it) eBay

 

[Deleted account]

Believe it or not the replacement was one of the cheaper makes.

Crompton.

I had just removed them from another property and replaced them with yet another make because they where breaking at a rate of one per month.

So it gets rid of inductive lighting, but has poor longevity.
Not ideal.

As a result of these issues I no longer supply g9 LED bulbs, I give the customer the task of sourcing and buying them. No come back on me.

 

[w0z]

Hi,

I'm looking for some advice on LEDs that glow when switched off in a multi-switch circuit.

Last month I replaced our old CFL lamps with multiple LED G9 'chandeliers'. The living room has a dimmer switch and the 20-odd LEDs all work fine.

However the hallway has 3 ceiling fixtures, with about 20 G9 LEDs, and 3 switches - one upstairs and 2 downstairs. They have the same LEDs as the living room but they won't stop glowing -when they are switched off they are almost as bright as when switched on.

Switching the RCD off switches the LEDs off.

My googling leads me to believe that the 40V I can see between live/neutral on the ceiling fixture, when off, is inductive voltage/capacitive coupling. I did buy a "0.1uF + 100 Ohm 250VAC triac snubber" from ebay but it didn't seem to have any effect, and the only other capacitor/resistor I found on my browsing linked to a maplin product.

I had one halogen G9 lying around which I put in the place of a single LED and it, too, glowed weakly as the LEDs shone brightly.

And that's how I've left it for a month but as June 21st has come and gone I need to sort this out. I have learned about as much as I can and am still no closer to a recognised solution.

What can I do to pin this down?

Thanks,

Have you measured the current to the fitting with the lamps switched off?

 

[Stagbeetle]

Thanks Pete - I'll google them and 'fancy' brands to see if I can find a common factor.

Taylor - I wish I had bought the lights a month earlier when there was a local Maplins! In terms of RSC I find the choice a little overwhelming since I'm not sure if the snubber resistance/capacitance is a standard value or related to measurements on the circuit. I thought the ebay one I got would at least show some improvement even if the values were wrong:
0.1uF + 100 Ohm 250V 250VAC RC network contact suppressor triac snubber Qty1 | eBay - https://www.ebay.co.uk/itm/123075894023

 

[Stagbeetle]

Have you measured the current to the fitting with the lamps switched off?

No, I haven't... I guess that would help pin down a snubber value?

 

[Wilko]

Maybe the circuit polarity is incorrect? If the L remains connected to the LEDs there may just be enough capacitive coupling to get a glow. It's just a thought. But can you confirm L is not present at the light fitting when it's off? Any test gear?

 

[Taylortwocities]

100R+100uF is the usual jobby and is usually effective.

 

[Stagbeetle]

Maybe the circuit polarity is incorrect? If the L remains connected to the LEDs there may just be enough capacitive coupling to get a glow. It's just a thought. But can you confirm L is not present at the light fitting when it's off? Any test gear?

I just have a DMM and a Maplin analog meter. I guess I'm also working on the assumption that the previous CFLs worked fine with the same circuit (and, possibly noteworthy) when I replaced just the first CFL the LEDs all flashed as (I presume) one CFL took the voltage until it triggered and all the LEDs flashed momentarily and the cycle started again.
With them all replaced I'm getting a glow from the halogen but the LEDs are too-bright to be called 'glowing' - they look 'on' (tbh they are too bright when really on so I may end up replacing them one day anyway).
I'm fairly certain I have to assume it's inductive/capacitive unless there's a simple test I can do to eliminate that (and the simplest seems to be to insert a better snubber in the circuit).

 

[Stagbeetle]

100R+100uF is the usual jobby and is usually effective.

100uF ? I thought I was looking at 1uF...
Have you got a link or something I can 'buy now' because I know there's other considerations (X2? 300V etc)

 

[Taylortwocities]

Apologies. It should be 100R + 0.1uF

Too much football lager.
See link in post #8

 

[Wilko]

For what it's worth, I've not seen a halogen lamp glow when the circuit cabling is correct and the switch is off. Makes me think there is a fault here (?).

 

[w0z]

No, I haven't... I guess that would help pin down a snubber value?

I doubt it as from your description I would be surprised if it's down to L a/o C coupling, I think you'll find it's mis-wired or there's some other fault. If the current is substantial that would help confirm this. What happens when you completely disconnect the switch?

 

[Marvo]

.......With them all replaced I'm getting a glow from the halogen but the LEDs are too-bright to be called 'glowing' - they look 'on' .....

Forget the L-C snubber, if the halogen lamp is glowing find the fault. Also assume everything on this light circuit is live and is going to give you a shock even if it's switched off. Be very careful!

 

[Stagbeetle]

OK, thanks for all the replies... plenty to think about.

If a G9 halogen shouldn't be glowing then perhaps checking the current with the switch off is the next best thing to do.

Also - disconnecting a switch should bring the voltage back to 0V if this is inductive voltage, but it will remain >0V if I have another problem - is that right?
The other problem *could* be induction from another live wire (e.g. the upstairs hallway light 2-way circuit) so a current test would be needed to eliminate coupling?

I'll see if I can get some meter readings.

With mains electricity I assume everything is out to get me

 

[Marvo]

.......The other problem *could* be induction from another live wire (e.g. the upstairs hallway light 2-way circuit) so a current test would be needed to eliminate coupling?

If the halogen lamp is glowing as well as the LED's this would rule out any type of capacitive or inductive coupling.

 

[Stagbeetle]

OK, just disconnected the crossover switch and the lamps do not glow in one switch position. Does this prove they are not getting live from a second circuit?

Current at crossover recorded 60-70mA when 'on' and 2-3mA when off.

I'm afraid I have no idea what to make of that.

There are 14 5W LEDs and 1 halogen (not sure wattage) but - oddly - only 9 LEDs and halogen glowed when 'off'. I think if I put the LED back in place of the halogen they'd all glow.