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.

 

[Mike Johnson]

Snubber across the LED connection.

 

[Avo Mk8]

If I understand correctly, rather than a fan with an integral run-on timer, you have a standard fan with a separate external timer unit connected in the wiring to the fan. Could you confirm it's done as the circuit below (with the neutral not switched) but with the timer connected after the switch to the three fan feeds?
If the run-on timer has any significant leakage from its live input to its switched live out, this could be the cause of the led's illuminating.
as above re snubber - but It may not be like an induced/ghost voltage that can be shunted, so that may not be the solution.

What is the model of the run-on timer for interest, because I'm thinking at the moment that may be the culprit?

 

[clanky boy]

If I understand correctly, rather than a fan with an integral run-on timer, you have a standard fan with a separate external timer unit connected in the wiring to the fan. Could you confirm it's done as the circuit below (with the neutral not switched) but with the timer connected after the switch to the three fan feeds?
If the run-on timer has any significant leakage from its live input to its switched live out, this could be the cause of the led's illuminating.
as above re snubber - but It may not be like an induced/ghost voltage that can be shunted, so that may not be the solution.

What is the model of the run-on timer for interest, because I'm thinking at the moment that may be the culprit?

View attachment 109798

Thank you for replying.

The timer is a Manrose 1351. The fan, buried in the ceiling! has a built in timer set to max (30mins), and i adjust the overrun time on the external timer. The supply to the fan isolator DP switch is last on the lighting radial. It then goes to the timer and the output from the 1351 timer to the fan. The 1351 timer needs a SL so I have taken a SL from the light switch to timer, to control the timer start function. Output from the timer then to fan. The fan needs a SL in its JB so i have looped the fan L to SL in the fan JB.
All functions correctly except the LEDs flicker dimly unless the DP switch is open.

I have two bathrooms with the same issue, all wired the same.

I tried to load a wiring diagram but it was 3.2Mb and it wouldn't accept it I'm afraid!

Thank you for helping.

 

[James]

Is the circuit protected by and rcd?

 

[clanky boy]

The circuit is protected by an RCBO.

 

[Mike Johnson]

You have complicated the connections unnecessary.

https://www.tlc-direct.co.uk/Technical/DataSheets/Manrose/BGDT20_1351.pdf

 

[Avo Mk8]

All functions correctly except the LEDs flicker dimly unless the DP switch is open.

I think it's significant that the Manrose timer spec gives not only a maximum load, but also a minimum load of 15W!
I'm suspicious of leakage current coming out of the switched live terminal of the Manrose timer when the lights are off, causing the led flickering effect.
If a snubber across the bathroom led's doesn't fix it, I'm not sure what's next best.
You could fit a relay across the lights and use the n.o. contact to energise the Manrose SL input!
If the bathroom LED's are of an interchangeable type, eg GU10 holders, as a bodge you could put a single halogen bulb in one of them, which should stop the flickering of the rest!
Or use a double pole light switch with one pole for the Manrose SL and the other for the lights!
Or try a different overrun timer!

I tried to load a wiring diagram but it was 3.2Mb and it wouldn't accept it I'm afraid!

If using a tablet or PC you might try taking a screen shot, editing out anything spurious round the edges, and uploading that!

 

[Avo Mk8]

You have complicated the connections unnecessary.

https://www.tlc-direct.co.uk/Technical/DataSheets/Manrose/BGDT20_1351.pdf

I understood that's what's essentially been done, but the switch shown is also the light switch!

 

[Mike Johnson]

I have the same unit to control my shower fan, it switches two independent LED GU10's in the shower cubicle without any flickering, but then I did wire it in accordance with the wiring diagram in post 7 between the SL and N into the Manrose unit after the switch.

 

[Mike Johnson]

I understood that's what's essentially been done, but the switch shown is also the light switch!

And I think that is where the problem is, Ghost voltage from the main switch, a snubber should sort it out, two way by chance?

 

[Avo Mk8]

I have the same unit to control my shower fan, it switches two independent LED GU10's in the shower cubicle without any flickering, but then I did wire it in accordance with the wiring diagram in post 7 between the SL and N into the Manrose unit after the switch.

So the switched feed to your LED's is connected to pin 2 of the Manrose thing, they are less than 15W, and they don't flicker!
So much for my theory!

 

[clanky boy]

And I think that is where the problem is, Ghost voltage from the main switch, a snubber should sort it out, two way by chance?

The timer is wired as per instructions and ligjting load is 4x4.8w LEDs, and to act as a snubber I wired the shower light which is a gu10 as the last lamp on the run. I have also tried two (in case one was duff!) 47uF 100r capacitor across every combo of terminals - I'm baffled.
I'm going to try a 1 way switch at the light switch as I am using a two way but in 1 way config.

I really appreciate all the help and advice - I'm struggling with this one!!

 

[Mike Johnson]

Have you tried the capacitor across one of the LED's?

 

[clanky boy]

Have you tried the capacitor across one of the LED's?

I have, on the first LED in the run, where I switched them. I'll try one of the others now though. I have just changed the switch to a 1w as opposed yo the 2w that I was using - back soon!

 

[Mike Johnson]

To stop the stray voltage in my kitchen flashing the LED's I had to use snubbers on four of the twelve lights.

The one way switch as opposed to a two way would only make a difference if wired two way.

 

[clanky boy]

I have, on the first LED in the run, where I switched them. I'll try one of the others now though. I have just changed the switch to a 1w as opposed yo the 2w that I was using - back soon!

I have fitted the capacitor across one oc yhe other LEDs and no change and swapped 2w for 1w switch.

 

[clanky boy]

I have fitted the capacitor across one oc yhe other LEDs and no change and swapped 2w for 1w switch.

Managed to upload screenshot of wiring - sorry for rubbish art skills!!!

 

[clanky boy]

Managed to upload screenshot of wiring - sorry for rubbish art skills!!!

Not drawn on sketch is DP switch just before timer (between 1st LED JB and timer on sketch).

 

[Mike Johnson]

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

 

[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, 630V dc 1-way , Through Hole, PMR209 | 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.