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.

 

[Stagbeetle]

Actually not sure if that was clear - I'm new to crossover switches so I'll explain it better.

I disconnected one wire from crossover switch and a helper switched the lights on/off with the 1st or 3rd switch. When 'off' the lights didn't glow, I put it down to the 'off' circuit being broken at the crossover wire I pulled.

I then put a DMM on the pulled wire and measure 60-70mA and 2-3mA whilst helper used the other switch.

With the ammeter connected the LEDs did glow when off - ie the current was being drawn through the crossover switch.

I'm not really familiar with AC either so if that terminology is wrong assume I'm in thinking in DC

 

[Wilko]

Hi - you've tried your best, but IMHO you should make friends with a real Electrician now. Us virtual ones can't be there to keep you safe doing what you're doing.

 

[Stagbeetle]

Thanks, but I'd like to understand what I've found out so far... I think with the suggestions above I've disproved miswiring in the ceiling (ie anything after the crossover switch), and with a 3mA current when 'off' I think it's proved to be either miswiring before the crossover or capacative coupling - so it comes down to whether 3mA is a reasonable figure for CC?
If it is then I can go down the 'try a different LED' route before I get an electrician?
(I actually spoke to 2 acquaintances who are electricians and they both looked at me as though I was mad - "voltage cannot be 40V when 'off'"! - so I'd prefer to find someone who has seen this before)

 

[w0z]

I agree with Wilko

In the famous words of Dragons' Den "I'm out" but I will extend you the courtesy of telling you why.
This is one of the most confusing threads I've read on here and begins with many incorrect assumptions and much missing information, but the dealbreaker for me is that I don't feel that you understand what you're doing and that you don't really understand electricity at all. That makes you a danger to yourself and others. I'm sorry if that sounds harsh.

Crossover switch? Do you mean intermediate switch? (where was that in the original post?)
Who connected the lights?
Did they ever work properly in the first place?
Did you draw a diagram of your wiring?
Could you (draw a diagram)?
Would you know if the lights were ever working correctly? (it's not obvious with some leds).

My guess is some of the lights are or have been incorrectly wired in series with each other when off, in some way, perhaps dangerously which is why you're measuring 40v, but frankly I don't trust any of your measurements anyway.

By the way 14 x 5w leds = 70W (estimate as leds inexact) Halogen? 10W? 20W?
I'll leave you to work out the theoretical current (with pen and paper please, not with a screwdriver and DMM). Clue- it's more than 70mA

 

[Stagbeetle]

I agree with Wilko

In the famous words of Dragons' Den "I'm out" but I will extend you the courtesy of telling you why.
This is one of the most confusing threads I've read on here...

Crossover switch? Do you mean intermediate switch? (where was that in the original post?)
Who connected the lights?
Did they ever work properly in the first place?
Did you draw a diagram of your wiring?
Could you (draw a diagram)?
Would you know if the lights were ever working correctly? (it's not obvious with some leds).

My guess is some of the lights are or have been incorrectly wired in series with each other when off, in some way, perhaps dangerously which is why you're measuring 40v, but frankly I don't trust any of your measurements anyway.

By the way 14 x 5w leds = 70W (estimate as leds inexact) Halogen? 10W? 20W?
I'll leave you to work out the theoretical current (with pen and paper please, not with a screwdriver and DMM). Clue- it's more than 70mA

Thanks for telling me why - but if you would bear with me I think I can clear up a lot of your points...

The crossover/intermediate switch was assumed because there are 3 switches so there has to be one, right? When asked to disconnect a switch I picked the middle one.

The original CFL lights did work fine.

I put up the new lights - one-for-one replacements, I don't see how I could have miswired them.

The 'off' voltage is definitely there, measured with DMM and analog meters.

I do understand electricity and I put the 63mA as the observed measurement rather than calculate it. The AC calculation is different from DC and, I admit, 'power factor' means little.

However I'm happy with the 63mA because -as you say - LEDs are inexact and I'm happy to assume my DMM is not calibrated... I see the important thing as proof the current is being drawn through the crossover switch, and if I disconnect that then the LEDs go off - proving no other source of current after the switch.

Don't worry if you want to stay dropped out, I'm not getting bolshy about it, I know how these things can be difficult over a forum... however I got such useful replies at the beginning I just wanted to follow up on them in the hope of a diagnosis.

In short, am I right in thinking it's still induction/CC? Can that generate 3mA ? Or is there a way to calculate CC from the length of live wire going back and forth over the 3 switches?

 

[DPG]

Several people above have answered your question about the stray voltage being capacitive /inductive pickup across adjacent cables. Very unlikely to illuminate a halogen lamp.

Needs a sparky in to do some thorough testing.

 

[davesparks]

Capacitive coupling is normally enough to cause an occasional flash from LED or CFL lamps as the capacitors in the drivers very slowly charge and discharge.
For a halogen lamp to glow when switched off I’m pretty confident in saying something other than capacitive coupling is not responsible for this.
Capacitive coupling occurs in conductors which are floating (not connected to a source of power or neutral/earth. The halogen lamp is effectively a simple piece of wire which shorts the switched live to neutral and so negates any capacitively coupled voltage when switched off.
For the lamp to glow the switched live must still be connected to a source of power, and since it is only glowing and not at full brightness I’d say that connection has some appreciable resistance to it.

My guess would be a faulty switch or a joint box with something in it that shouldn’t be there, water or a mouse etc.

 

[Chris1234]

I agree with the above about getting an electrician to look at it.

If it is induction then it’s likely you can connect a contactor above the ceiling light somewhere and have the switches operate that. The contactor will disconnect live and neutral from the supply when not in use.

I think even in industry in control panels with hundreds of wires grouped together with tens of motor drives close by, I’ve never seen induction as high as 40 volts!

 

[w0z]

Thanks for telling me why .....

In short, am I right in thinking it's still induction/CC?

I doubt it.
Please read the answers you've been given so far.

 

[w0z]

I agree with the above about getting an electrician to look at it.

If it is induction then it’s likely you can connect a contactor above the ceiling light somewhere and have the switches operate that. The contactor will disconnect live and neutral from the supply when not in use.

I think even in industry in control panels with hundreds of wires grouped together with tens of motor drives close by, I’ve never seen induction as high as 40 volts!

OP' has now been told 3 times that it's very unlikely (read not) induced.

 

[davesparks]

I think even in industry in control panels with hundreds of wires grouped together with tens of motor drives close by, I’ve never seen induction as high as 40 volts!

Im pretty sure you will have seen induction at much higher voltages than that considering induction is the basis of how generators, transformers and motors operate

 

[Chris1234]

Im pretty sure you will have seen induction at much higher voltages than that considering induction is the basis of how generators, transformers and motors operate

Yes of course, like the 15kva transformer I was working on yesterday.
But we were talking about unwanted induction between circuits in a residence.

 

[Stagbeetle]

OK, thanks for all of your help.

I understand that the glowing halogen has killed the induction theory, which is a shame because I felt that was probably curable.

Ironically I did change some LED bulb brands and when they didn't glow I thought it was solved, but on removing the halogen they did glow.

I agree it now requires proper testing of the circuit which I'm happy to delegate.

I'm still curious though about the theory of what is happening - if the rogue current is only there when the RCD is closed, the live wire is the only possible source... correct?

So if there is a fault with the live wire, and if it is before the switches, the fault won't be detectable - ie the switches will still cut out the rogue current.

And yet if there is a fault after the switches then the LEDs would have glowed even after I disconnected the crossover switch - but they only glowed when I closed the circuit with the ammeter (and saw the 3mA).

Apologies if my question is too 'DC'-like