GU10 flashing when turned on, work if load added to circuit

steveKN · Nov 7, 2024

A strange one in my kitchen.

3 sets of 2-way switched GU10 `Philips down lighters. ( no dimmers)

Have been fine for several years.

Last week the fan/light remote receiver, ( connected via a on/off wall switch, using live which also goes to lights, neutral permanently connected to lighting circuit) on the adjacent conservatory, died tripping the miniature circuit breaker on the lighting circuit.

Removed and waiting for replacement.

Now the 3 LED sets ( 2x2 and 1x4) strobe flash when turned on.

If I turn on another light (non GU10) or fan to produce a load on the live-neutral spur circuit to the kitchen or conservatory, the LED GUI0 work fine, (but no with a load on any other part of the shared downstairs lighting circuit.)

They will still stay on if I turn the extra load off, unless I turn another of the light LED circuits on, then they all flash again, until I add another load when they all come on and all remain on. ( even again with load turned off)

I've checked the 3 switch live connections at either end of the two-way switching, and they're fine.

Any other suggestions ? They all have a common neutral and are fed from the same live from the switches.?

Thanks Steve

brianmoooore · Nov 7, 2024

The problem is being caused by capacitive leakage between the strappers of the 2W switches, giving rise to a voltage at the lamps which builds until the LEDs fire, discharging the voltage. Repeat.
The usual solution is to add 'snubber(s)', consisting of a resistor and capacitor in series.
Search eBay for "rc snubber".

steveKN · Nov 8, 2024

brianmoooore said:
The problem is being caused by capacitive leakage between the strappers of the 2W switches, giving rise to a voltage at the lamps which builds until the LEDs fire, discharging the voltage. Repeat.
The usual solution is to add 'snubber(s)', consisting of a resistor and capacitor in series.
Search eBay for "rc snubber".

thank you, i can understand why the lights fiash when OFF but mine flash when turned ON and will nit fully light until an extra load is added to the circuit. would snubbers help in this circumstance ?

Avo Mk8 · Nov 8, 2024

steveKN said:
thank you, i can understand why the lights fiash when OFF but mine flash when turned ON and will nit fully light until an extra load is added to the circuit. would snubbers help in this circumstance ?

I don't think snubbers would help here.
The lights are behaving as if there is a high(ish) resistance in series with them when they are on, but that resistance reduces when you turn on other things on the circuit. Could it be that the removal of the fan/light receiver has resulted in an unintended wiring change?
(Or an error in the original wiring that has only now become evident since the removal of the receiver!)

brianmoooore · Nov 8, 2024

As Avo Mk8 has written above. I really must learn to read posts more carefully before replying!

steveKN · Nov 12, 2024

Avo Mk8 said:
I don't think snubbers would help here.
The lights are behaving as if there is a high(ish) resistance in series with them when they are on, but that resistance reduces when you turn on other things on the circuit. Could it be that the removal of the fan/light receiver has resulted in an unintended wiring change?
(Or an error in the original wiring that has only now become evident since the removal of the receiver!)

thanks, yes the lights are working now if I have the replacement remote receiver connected. ( if I turn it off at the wall switch, get my flashing light until load problem back) so it properly has all ways been like that. ( the kitchen down lighters were originally non led mains GU10s). If I replace just one downlight with an old 3 chunky ( slightly green!) led? GU10 that circuit is also fine)
Any suggestions what could cause these symptoms ( high resistance which reduces when loaded ?)

thanks Steve

Avo Mk8 · Nov 12, 2024

steveKN said:
thanks, yes the lights are working now if I have the replacement remote receiver connected. ( if I turn it off at the wall switch, get my flashing light until load problem back) so it properly has all ways been like that. ( the kitchen down lighters were originally non led mains GU10s). If I replace just one downlight with an old 3 chunky ( slightly green!) led? GU10 that circuit is also fine)
Any suggestions what could cause these symptoms ( high resistance which reduces when loaded ?)

thanks Steve

It does seem to me that there's a capacitively coupled voltage to each set of downlights (on the light side of the switch), and when you put the receiver in circuit, it drains that.
This is probably not a 'fault' situation, but an artefact of some cables being close to each other and also having bulbs that are able to charge up from the stray voltage and 'strike'.
So I'm thinking brianmoooore was probably right about a snubber helping the situation, and one across a downlighter on each of the circuits might do the trick. This sort of thing has been suggested in the past here: