Flashing LEDs when fan and lights off

[clanky boy]

Good afternoon everyone.
I have fitted an extractor fan in my bathroom with an overrun timer, to start when the bathroom led lights are turned on. I have wired the feed to the fan via an adjustable overrun timer and DP isolator with the SL for the fan timer coming from the light switch.

The issue is with lights and fan off the LEDs are flickering dimly - this stops when the DP switch is opened. I assume there is a small leakage to N from somewhere in the timer causing the sensitive LEDs to flicker, which when the DP switch is opened cannot occur hence the flicker stops.

I have bought and fitted a 47nF 100r capacitor and connected it to all possible combos in the timer - no change. The only thing that stops it is if I disconnect the SL from light switch yo timer - but obviously the fan wont run now.
I have spoken to a qualified sparky who's only suggestion was the capacity action as a snubbed - he doesn't know what to do now!

I am stumped and would appreciate any advice please.

 

[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.

 

[Mike Johnson]

@clanky boy notwithstanding any of the last four pages, somewhere you have a Ghost voltage on your supply to these lights, this can be caused by many different reasons, but usually its a two way switch somewhere on the loop with an induced voltage between the two switch's, a clean supply or snubber/snubbers are the only way to cure the problem IMO.

 

[clanky boy]

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!

I have ordered a few 150nF and I'll try that - if no joy I'm off to tie a noose!!!
Thank you everyone for the help and advice - if the new snubbers don't work I'll pick this up again.

 

[clanky boy]

I use these from RS Components:

View attachment 109812

That is a nice tidy setup - I will try these if what I have ordered doesn't work.
Thank you.

 

[Mike Johnson]

@clanky boy any news?

 

[clanky boy]

@clanky boy any news?

Not yet Mike. The snubbers arrived Fri and not had a chance to fit them yet. When I do I'll post the outcome- it's always nice to close a problem down and not leave it open ended