Voltage on light circuit when off

[Lucien Nunes]

No, only one per SL regardless of how many lamps it serves, as they are all in parallel. The snubber can be placed anywhere - at one of the lamps, in the rose, in a JB where the SL and N are accessible - to bleed that SL down to N and therefore stop any and all lamps on that switch flashing.

Does anyone have experience of what value of capacitor is typically needed? I would expect 0.1μF to be fine, Xc is about 32kΩ at 50Hz, so even 100's of μA of leakage would only produce a few volts at the lamps.

 

[gazdkw82]

One per switched line, it's bleeding off the leakage from SL to N instead of it passing through the lamp(s).

No, only one per SL regardless of how many lamps it serves, as they are all in parallel. The snubber can be placed anywhere - at one of the lamps, in the rose, in a JB where the SL and N are accessible - to bleed that SL down to N and therefore stop any and all lamps on that switch flashing.

Does anyone have experience of what value of capacitor is typically needed? I would expect 0.1μF to be fine, Xc is about 32kΩ at 50Hz, so even 100s of μA of leakage would produce a few volts at the lamps.

Does it make an difference that there are 2 circuits effected?

Should it be 1 snubber per SL and N, for each circuit?

 

[Lucien Nunes]

Yes. Each SL is a separate, floating 'leakage collector' when it is switched off. It needs to be bled down to its own neutral.

 

[Mark Wright]

Probably switch on the Neutral and not the live, quite dangerous really.

 

[DPG]

Probably switch on the Neutral and not the live, quite dangerous really.

Why do you think the switch is in the neutral? Apologies if I've missed something.

 

[Lucien Nunes]

Probably switch on the Neutral and not the live, quite dangerous really

Unlikely, since in post #9 they reported the switched feed to be 230V from earth with the lights on, and 79V from earth with them off.

 

[Mark Wright]

Sorry I thought he tested between Line and Neutral. I was going to suggest test between Live and Earth at light when switch off.

I have seen something similar and the Second switch was off the first Switch Live and Switch Line in T&E.

 

[gazdkw82]

Any advice as to what value would be needed?

 

[DPG]

Have a google on snubbers, there are ready made ones available that will have the values stated on them.

 

[Lucien Nunes]

0.1μF is common, I can't see that a larger value would be needed for any reasonable amount of leakage, and the larger case would be harder to fit in a back box or wherever it's going.

BTW did you ever do any insulation tests on the switching as I recommended? It would be good to confirm that you are not simply concealing an actual fault.