Flashing LEDs when fan and lights off

[clanky boy]

Put on an additional snubber and re-draw your sketch.

Mike, please see a better diagram. I have now fitted two capacitors (only have 2) and no change. I would have thought two capacitors and a gu10 should quash any stray V? As soon as I disconnect the timer SL the flickering stops. Can I fit a 10a 250v diode to stop any voltage leakage back from the timer SL to the SL connection at the light switch, which is the only way I can see and voltage getting to the LEDs.

 

[Avo Mk8]

Can I fit a 10a 250v diode to stop any voltage leakage back from the timer SL to the SL connection at the light switch, which is the only way I can see and voltage getting to the LEDs.

It's ac mains. A diode will just rectify it, the result of which probably won't do what you want!
Is the S/L from switch to timer accessible? Would it be practical to use a 2 pole light switch and switch the timer S/L separately from the LED's? That would obviously stop the problem!

Could you confirm if the GU10 is LED or halogen. If LED could you try a halogen?

Sorry about all the questions - your circuit diagram rather neatly separates the wiring of the timer and fan from the wiring of the lights, but in reality are the physical cables jumbled together? That could lead to an induced voltage being the problem.
But if they are actually separated, I'll stick with the suggestion it might be the timer creating the voltage.

 

[clanky boy]

It's ac mains. A diode will just rectify it, the result of which probably won't do what you want!
Is the S/L from switch to timer accessible? Would it be practical to use a 2 pole light switch and switch the timer S/L separately from the LED's? That would obviously stop the problem!

Could you confirm if the GU10 is LED or halogen. If LED could you try a halogen?

The gu10 is a halogen, which I thought would sort any voltage leakage.

 

[Avo Mk8]

The gu10 is a halogen, which I thought would sort any voltage leakage.

I absolutely agree. I can't see how it can be induced voltage from other wiring with a thumping great filament load across it.

 

[clanky boy]

I am now confused. I will look for a DP switch and try that if you think that is ok?

 

[Avo Mk8]

I am now confused. I will look for a DP switch and try that if you think that is ok?

Well it would stop the flashing, but doesn't explain why it's happening!

Have you got a multimeter or MFT?

 

[Mike Johnson]

Have you disconnected the SL from the L in the fan?

 

[clanky boy]

Well it would stop the flashing, but doesn't explain why it's happening!

Have you got a multimeter or MFT?

Yes, a multimeter

 

[Avo Mk8]

Yes, a multimeter

Thought it might be worth measuring voltage on Manrose S/L, both connected and disconnected.
Also try Mike Johnson's suggestion above.

 

[clanky boy]

Thought it might be worth measuring voltage on Manrose S/L, both connected and disconnected.
Also try Mike Johnson's suggestion above.

Good morning everyone. As mike suggested I disconnected the SL at fan - no change.
I have fitted a different timer - no change.
Cables are not particularly close or bunched - so I think unlikely it's inductive from an adjacent cable.
Showing between 7v - 11v between L/N at one of the LEDs.

I have wired a pendant with 100w lamp across one of the LEDs L/N and problem gone, but obviously I can't keep that there!

I'm using .47uf 100r capacitor as snubber, but are these large enough (or whatever), as the 100w lamp appears to be able to dissipate the stray voltage.

Yet again I appreciate all the help.

 

[Avo Mk8]

Good morning everyone. As mike suggested I disconnected the SL at fan - no change.
I have fitted a different timer - no change.
Cables are not particularly close or bunched - so I think unlikely it's inductive from an adjacent cable.
Showing between 7v - 11v between L/N at one of the LEDs.

I have wired a pendant with 100w lamp across one of the LEDs L/N and problem gone, but obviously I can't keep that there!

I'm using .47uf 100r capacitor as snubber, but are these large enough (or whatever), as the 100w lamp appears to be able to dissipate the stray voltage.

Yet again I appreciate all the help.

Thanks for all the info. It doesn't get any clearer!
Have you tried disconnecting S/L from the timer and measuring the voltage on the 'Manrose' S/L terminal (if any).

I'm presuming all the lamps (by which I mean the bulbs themselves) on this circuit are mains voltage, there's no led driver or electronic transformer on this circuit, no shaver socket or charger, or anything we're missing?

 

[Avo Mk8]

It would help me if you could disconnect the entire LED string (complete with the shower light) from its supply, eg at the terminal block or whatever it is that you show in your diagram, and measure the resistance of the lamp chain between L and N. I would expect it to be very low, eg 10 or so ohms with the shower halogen bulb in circuit.

 

[clanky boy]

Thanks for all the info. It doesn't get any clearer!
Have you tried disconnecting S/L from the timer and measuring the voltage on the 'Manrose' S/L terminal (if any).

I'm presuming all the lamps (by which I mean the bulbs themselves) on this circuit are mains voltage, there's no led driver or electronic transformer on this circuit, no shaver socket or charger, or anything we're missing?

I will measure the V at the SL at the timer.
The spots are 240v ovio inceptor nano5.
The Halogen is not mains voltage, it's 12v from a Tx just before the light that is set into the extractor inlet over the shower.
I might disconnect the Tx and see if that does anything.

 

[clanky boy]

It would help me if you could disconnect the entire LED string (complete with the shower light) from its supply, eg at the terminal block or whatever it is that you show in your diagram, and measure the resistance of the lamp chain between L and N. I would expect it to be very low, eg 10 or so ohms with the shower halogen bulb in circuit.

I'll go and do that now - back shortly.

 

[Avo Mk8]

I'll go and do that now - back shortly.

Sorry, sent you on a wild goose chase!
I had the feeling the shower light couldn't be mains halogen with what we've seen, as it's not acting as a snubber!

If you put a mains halogen somewhere in that chain, that would be one way of solving the problem.
I think Mike is right, it just needs more snubbers until the effect goes away.

 

[clanky boy]

I'll go and do that now - back shortly.

The voltage at SL is 11.4v.
All LEDs and halogen, 2 snubbers and 100w lamp - approx 100M ohms
All LEDs and halogen, 2 snubbers- 90M ohms
All LEDs and halogen, 1 snumber- 100M ohms
All LEDs and halogen, - 120 - 150M ohms.

 

[clanky boy]

The voltage at SL is 11.4v.
All LEDs and halogen, 2 snubbers and 100w lamp - approx 100M ohms
All LEDs and halogen, 2 snubbers- 90M ohms
All LEDs and halogen, 1 snumber- 100M ohms
All LEDs and halogen, - 120 - 150M ohms.

I have taken a picture of the 2 snubbers I have - are these suitable or can you recommend something else please.

 

[Avo Mk8]

I have taken a picture of the 2 snubbers I have - are these suitable or can you recommend something else please.

The 47nf is maybe a little low. I think 100nF (0.1uF) or more with say 120 ohms in series is the usual sort of thing.
There have been threads on this forum before about this.

This has been a suggestion before:

PMR209ME6220M470R30 | KEMET RC Capacitor 220nF 470Ω Tolerance ±20% 250 V ac, 630 V dc 1-way Through Hole PMR209 Series | RS

uk.rs-online.com

You may still need more than one!

 

[Mike Johnson]

I use these from RS Components:

 

[Avo Mk8]

I use these from RS Components:

That's the one! I think it was your post I was thinking of.