LED downlights glowing when switched off.

[RWD3M]

Hi All,

I replaced half a dozen 40w downlights in the kitchen with these new fangled LED ones.

All I did was replace them one for one and was even lucky enough to find ones that fitted the existing holes.

However, I have now noticed a strange phenomenon. They glow, albeit very dimly, when switched off.

Internet research suggests this is not an unusual thing but but I'd like reassurance from those in the know rather than some random bloke off the web!

 

[Nick DV]

It's not a problem and common. Plenty of good info on the web, just one example https://www.rowse.co.uk/blog/post/why-do-my-led-lights-glow-after-being-turned-off

 

[MetalMonkey]

Induced phantom voltage/capacitive coupling is likely the culprit - it only takes a very small amount to light them, especially common on two way lighting. You get a similar issue with CFLs pulsing.
Some lamps are more and less prone to it. Often changing the LED to a different make/model will resolve it. Other options you could look at is adding a snubber.
First thing to do is to get a meter on it and check

 

[Bouledogue]

We have a lamp that does this. Scared me at first, but an electrician friend put my mind at rest.

 

[RWD3M]

Thanks for the advice chaps, I'll now be ignoring it.

 

[Seadog]

You could fit a load of these.

Pardon our interruption...

One across each led.
If there are leds in parallel then you only need the one in that circuit.

 

[Pete.]

I had this on my workshop LED's. Switching the live and neutral wires over cured it.

 

[RWD3M]

You could fit a load of these.

Pardon our interruption...

One across each led.
If there are leds in parallel then you only need the one in that circuit.

Hmm... may do. There are 6 downlighters in the circuit so one should do then?
0.22 or 0.33 or doesn't it matter?

 

[tigdlo]

I had this on my workshop LED's. Switching the live and neutral wires over cured it.

That's interesting, a couple of my GU10 leds glow for a minute or 2 after switching them off, I'll try turning them 180degrees.

 

[RWD3M]

I had this on my workshop LED's. Switching the live and neutral wires over cured it.

Where did you switch the wires?

 

[RWD3M]

Induced phantom voltage/capacitive coupling is likely the culprit - it only takes a very small amount to light them, especially common on two way lighting. You get a similar issue with CFLs pulsing.
Some lamps are more and less prone to it. Often changing the LED to a different make/model will resolve it. Other options you could look at is adding a snubber.
First thing to do is to get a meter on it and check

They are 2 way switched.

 

[Pete.]

Where did you switch the wires?

Where they connected to the lights.

 

[brightspark]

there a pain in the ar.se for it on 2 way lights a bit of residual current hangs around and makes them flicker

 

[RWD3M]

there a pain in the ar.se for it on 2 way lights a bit of residual current hangs around and makes them flicker

Fortunately no flickering just this very dim glow, which we can live with.

 

[brightspark]

Fortunately no flickering just this very dim glow, which we can live with.

that as well

 

[Seadog]

Hmm... may do. There are 6 downlighters in the circuit so one should do then?
0.22 or 0.33 or doesn't it matter?

It doesn't matter, you just need a bypass for the tiny tesidual current.