Trailing edge or Leading edge for LED downlights?

HappyHippyDad · Jan 17, 2014

I am about to fit 9 5W GU10 LED's.

I realise that a Leading edge dimmer can be used but as I have not fitted a dimmer for LED's before I wondered if it was a much better idea to use a Trailing edge?

Also, I was under the impression that I had to meet the minimum wattage requirement for the dimmer switch, so my total wattage would be 45W, so a 250W dimmer would be ok as its minimum rating is 25W.

However I came across this on the web: LED Dimmer Switch Compatibility - Technical Information ? Light bulbs, LED bulbs, halogen lamps, spot lights and tubes

How Many Light Bulbs Can Be Used With A Dimmer?

All dimmer switches have a minimum and maximum rating (watts). Unfortunately LED loading cannot be calculated the same way as a traditional Incandescent or a Mains Halogen light bulb. A good ‘Rule Of Thumb’ to apply ,which is used by most manufacturers, is to take the maximum rating of the dimmer switch and divide by 10 (or in other words use 10% of the Max rating). As an example if you have a dimmer switch with a maximum rating of 400w (rule of thumb translates to 40w) you can run 5no 7.1w Dimmable LED light bulbs (see example below for further explanation).

So this suggests I would need a 600W dimmer which cant be right!! (x10% = max 60W), have they got it wrong?

foresite123 · Jan 17, 2014

You could use an MK 1523WHILV which looks like a normal white dimmer but is capable of dimming LEDs at min 4w and max 70w.

Have done a few and have had no probs.

Before that I used to use a 1000w Varilight dimmer which worked very well.

HappyHippyDad · Jan 17, 2014

foresite123 said:
You could use an MK 1523WHILV which looks like a normal white dimmer but is capable of dimming LEDs at min 4w and max 70w.

Have done a few and have had no probs.

Before that I used to use a 1000w Varilight dimmer which worked very well.

Thanks foresite, how many LED's did you have on the one dimmer (maximum you've had)?