Flashing LEDs when fan and lights off

[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

 

[clanky boy]

@clanky boy any news?

Mike, apologies for delayed reply, but I finally got round to fitting the snubbers today. I got 8 x .1uF 120ohm and fitted all of them, one more each time. It has vastly improved but problem still there - that equates to .8uF and 960ohms! I disconnected them again and tried my 100w bulb again - problem goes instantly yet it equate to 500ohms and .41A, if my maths serves me correctly. Am I missing something or do I need much bigger snubber(s) say .22uF (220nF),470ohm snubbers- your thoughts please, kind regards, Mark.

 

[Mike Johnson]

If you know where the main power for the downlighter runs, put the snubbers as close to the first lamp as you can.

 

[clanky boy]

If you know where the main power for the downlighter runs, put the snubbers as close to the first lamp as you can.

I have put 7 snubber s into the first light JB. Flickers and then peters out over 30 seconds.

 

[DPG]

There's got to be more to this than just needing more and more snubbers chucking at it surely?

Not sure what though I must admit.

 

[Mike Johnson]

The snubbers need to be on each individual light not all bunched together, see post No 39 that is just one light connected at the lower end of the junction box.

Its the bulb that is picking up the Ghost voltage not the circuit.

 

[clanky boy]

The snubbers need to be on each individual light not all bunched together, see post No 39 that is just one light connected at the lower end of the junction box.

Its the bulb that is picking up the Ghost voltage not the circuit.

I had 8 spread across 4 lights at each Jb, but you said put them as close to the first light, hence all 7 on a short tail off yhebjb for the first light - I'll put them back on each light on then.

 

[Mike Johnson]

The snubbers should be across each bulb, not the junction box starting at the closest bulb to the main junction.

 

[clanky boy]

The snubbers should be across each bulb, not the junction box starting at the closest bulb to the main junction.

They were across each L/N at each blue 'click' connector at each light. Same as in you picture of the pmr209/connector box setup. Each light had one.

 

[Mike Johnson]

Are you using PMR209 snubbers? Your picture on the post above does not look like them.

 

[Avo Mk8]

The snubbers should be across each bulb, not the junction box starting at the closest bulb to the main junction.

i don't get why it matters where you put the snubbers.

I'm assuming our hypothesis is that the flashing of LED's is being caused by an 'induced' /capacitively coupled voltage arising from the circuits switched live conductor(s) close proximity to permanently live conductors.

If you consider the equivalent circuit of what's happening, you have the capacitance (and inductance?) of the coupling between the cables (no resistive component unless there's a fault!) , and the capacitance/resistance of the snubber, acting as a potential divider, with the lamps across the snubber side. The resistance of the copper wire is absolutely negligible in relation to the capacitances in play, so it can't matter where you put the snubbers - they are on the equivalent of a bus-bar whether you put them distributed along or all at one end. It's not as if there can be a gradient of induced voltage along the cable!

With 8 x 0.1uF not completely solving the problem, that implies the impedance of the coupling between L and SL is at least equivalent, which I find hard to believe.
The only thing I can think of is that somehow this ghost voltage is partly or mainly dc, the capacitors only dealing with the ac bit of course.
Is there any way the timer could be responsible for a dc component?

I would like to suggest that, if possible, an insulation resistance test is done on this circuit.
And I think it would be useful to map out the path of permanent live and switched live, in terms of where those conductors run parallel to each other in the cables, and see if an alternative source of the power, or an alternative way of wiring, removing most of those parallel paths, could reduce the impedance of the ghost voltage, if that's what it is!

 

[Avo Mk8]

........... could reduce the impedance of the ghost voltage, if that's what it is!

Sorry - I meant "reduce the ghost voltage" not the impedance of it - that would just make things worse!

 

[clanky boy]

Are you using PMR209 snubbers? Your picture on the post above does not look like them.

They are not pmr 209, but are equivalent rating. I'll get some mr209s ordered and try them - trouble is there are 30 odd types in RS and they don't have any with sh1 on them, like the ones in your picture Mike - does this matter - will any pmr209 do the job. .47uf, 1uf .22uf what rating do you suggest please?

 

[DPG]

I can't see how that would matter in this case. As long as the values are the same. It's only 2 components bundled together in one package.

 

[Avo Mk8]

Hi Clanky
TBH I'm not sure spending more on snubbers is necessarily the way to go.
Keep trying with them if you like, but I feel there is something else going on here.
Is it the case that disconnecting the SL from the Manrose timer stops the LED's flashing?
Could you confirm that?

 

[Avo Mk8]

Just to follow on from my previous post - things to try.
You originally said that turning off the DP switch to the fan stopped the led's flashing. Presumably that is still the case?
If so, can you try disconnecting the SL from the Manrose and see if that stops the flashing.
If it does, one way of solving the issue would be to install a DP light switch, which looks do-able from your sketch.

e.g. https://www.electricaldirect.co.uk/...-1-way-double-pole-light-switch-white-919713?



Otherwise could you, as a separate experiment, disconnect the halogen driver (mains side) and see if that makes any difference?
Sorry about all the questions/suggestions. This is an usual situation that snubbers are not easily resolving, and I'm concerned that 'fixing' it with snubbers would be just hiding an underlying cause that could be a fault or a 'feature' of one of the accessories.