UK Advice (please) regarding suppressor / "snubber" for LED lighting

[feisar32]

Hi all

Hoping someone might be able to advise. I've got two sets of LED lighting this is affecting. One is the plinth LEDs I originally raised a thread for some months back; one is two LED wall lights.

The problem I have is that, when the lights are off, they flash briefly every ten seconds (in the case of the plinth LEDs) and every twenty(ish) seconds in the case of the farthest LEDs wall lamp. Both sets of lights are switched; the wall lamps are switched individually, and can be switched from the three-way switch nearest the door, or from a single switch under each lamp. The plinth LEDs are switched both via a presence detector, and can be overridden by a standard grid-switch module

When I did some Googling, there was a thread I found elsewhere that suggested "[..] you can usually check for a small voltage on the switched live wire. If the circuit has two-way switching, this voltage will be more apparent on one of the "off" configurations rather than the other. Adding a suppressor (or snubber) to the circuit between the switched live and the neutral will solve the problem".

My brother-in-law is an electrician, but he says he's never heard of suppressors or snubbers. I wondered whether this issue sounds familiar to any of you and if so, whether the suppressor or snubber is the correct solution?

When I Googled snubbers, what I got back as an example was something like a "Danlers Low Load Capacitor for Low Energy Lamps" ... would that be the right sort of thing ... ?

One other query as well, if I may: anyone know of any 24v LED strip with a 50mm cut-point ... ? Or is it only 12v strip that can be put at those intervals?

Thanks in advance ...

 

[Papa Lazarou]

The last couple I bought were from eBay.

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They were fine. Cheap too.

Are these exact ones definitely suitable, they are only 47Ohms which is less than others have stated is necessary. What is the implication of this? Higher current across L&N when switched on therefore more consumption and possibly heat, but also better able to discharge smaller induced currents?

Thanks, Tom

 

[Lucien Nunes]

The current when energised is determined almost entirely by the reactance of the capacitor, which is much higher than the resistor. The main purpose of the resistor is to limit the peak current on transients. If the snubber is used to suppress switch contacts or a semiconductor switch, or as a dummy load to bleed off leakage, it limits the current when the switch closes, which saves wear on the switch. It also protects the capacitor from fast-risetime spikes on the mains damaging the dielectric.

Therefore the resistor value is not very critical in this application. Too low (a few ohms) and the switch suffers wear, too high (a few kilohms) and the benefit of the wattless load of the capacitor is lost and more heat is dissipated. The worst case peak current on a switch closure is uo * sqrt(2) / R so I would tend to go for 100 ohms or so to keep it to just over 3A. I would be more interested in the quality and durability of the cap than the value of the resistor.