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Trying to replace 11 kitchen GU10 spots with dimmable LEDS but...

Postby thecount » Sat Mar 27, 2021 10:25 am

Struggling a little with this one.

So thought it would be a good idea to replace 11 50W GU10 spots in my kitchen for these:

Dimmable GU10 LED Bulbs, 2700K Warm White Spotlight, 350LM Recessed Lighting Bulbs, 5W(50W Halogen Replacement), 38°Beam Angle, CE and ROHS Listed [Energy Class A+]

This is the pack I purchased:

At one end of the kitchen, I had a standard dimmer and the other end, a two gang switch, switches outside light off and can switch the kitchen off at that end too (no dimmer on that faceplace.

So I fitted the bulbs and guess what, no dimming, even though these state dimmable?

So I thought it must be the dimmer, so I purchased a dimmable faceplate and fitting this:

Result - kind of...... Yes, it dims... BUT at the other end with the two gang, it no longer switches off. OR does when I switch the dimmer side off?

Any ideas?
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Postby Mr White » Sat Mar 27, 2021 11:45 pm

I would say it is due to the incompatibilities you have.

The lamps page wrote:Fully Smooth dimming from 10%-100%, compatible with leading-edge dimmer switches.

The dimmer page wrote:Trailing edge technology

It also goes on to say

The dimmer page wrote:The maximum load per gang is 100 watts or 10 lamps (whichever is lower).

You have 11 lamps.
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Postby ericmark » Sun Mar 28, 2021 2:50 pm

I would guess due to inductive and capacitive linking on the interlinking cables between the two switches.

AC does not work like DC, you don't need a wired link for energy to pass, this is why the no contact voltage sticks work.

In most LED lamps you have a capacitor that limits current, then a full wave rectifier then a capacitor which smooths the AC to stop flicker, and a resistor it ensure on switch off the capacitors discharge. Plus of course the LED's.

The size of the leak resistor and the smoothing capacitor varies lamp to lamp, and the resistor produces heat, so with small physical lamps the smoothing capacitor and leak resistor are smaller than with big lamps.

The not switching fully off can be cured by putting a capacitor across the lamps, normally around 4µF some also have a small resistor, called either a load capacitor or a power factor connection capacitor they will remove the problem. However they need mounting some where, and they are too big to fit into many junction boxes or ceiling roses.

I used a Danlers Low Load Capacitor from CEF (0900-6730), Screwfix do Elkay 4µF Power Factor Correction Capacitor (1373G), TLC call it a Glowfix Load Regulator or Danlers Low Load Capacitors for Low Energy Lamps (DN CAPLOAD).

However the problem is how to fit it, due to physical size. I did manage to squeeze it in, then still had a problem with bulb flicker when on, I was using these [attachment=1]G9-small.jpg[/attachment] and I realised fitting one quartz lamp stopped flicker, but could not stop it with all LED, so [attachment=0]G9-big.jpg[/attachment] these break all the rules, no watts marked on them, no lumen marked on them, and so big physical size the frosted glass would not longer fit, but flicker stopped, and likely the not switching off would have also stopped without the load capacitor.

I would say get a quartz 10 watt bulb and just use one quartz bulb is the easy way out, if you want to play with load capacitors OK, but be aware you should not really dim quartz lamps, the whole idea of quartz lamps is the quartz is that hot the tungsten will not deposit its self on the quartz, but return to the tungsten, so putting it simple GU10 lamps should not be dimmed, I know we do, but if you do some thing you should not do, hard to blame lamp or dimmer switch.
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Postby thecount » Mon Apr 05, 2021 11:22 am

thanks for the responses, I'll look into it all
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