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.