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I replaced the halogen GU10 bulbs in my kitchen with LED bulbs... I'm really pleased with the results but as the bulbs I bought are dimmable, how do I know what dimmer switch I can use?

I did try them with a dimmer switch but they were flickering very noticeably so it must have been the wrong type of dimmer switch

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3 Answers 3

You will need to check the product packaging or manufacture website to see what types it is listed for. All of the Leviton and Lutron products I see at Home Depot lately have clear markings on the packaging.

Lutron marks them as C-L and Leviton calls them "Universal Dimmers".

If your lights are 12V then you need a magnetic dimmers for low voltage lighting.

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Are these 120v or 12v bulbs? If 12v, the dimmer must be compatible with your transformer. If 120v, Steven's advice should help you find one. –  TomG Jan 7 '13 at 1:38
    
They are 120v not 12v –  Edd Jan 7 '13 at 14:35
    
+1 for checking with the manufacturer. Dimmers on AC are Triac Switches. They basically shut off part of the sine wave, reducing the power duty cycle during both positive and negative swings. Incandescent bulbs, being a glowing wire have the ability to average out the lower power with a lower glow. CFL designed for dimming act like they're being fed a lower voltage and do the same power averaging. LED's are a very fast active element and unless the driver circuit is designed well, start to turn off under much reduced power settings leading to flicker. –  Fiasco Labs Feb 6 '13 at 4:39
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The vast majority of wall dimmers work well near their rated load and down to about 20 or 30% of it. Below that, they tend to "cut off".

Increasing the load to be closer to rated capacity improves the low end range. However, LEDs are so amazingly efficient, they are nowhere near the dimmer's capacity.

You have three basic choices:

  1. Add some load along with the LEDs, like maybe a 60 watt incandescent, or a lot more LEDs. That will get the dimmer load closer to its design parameters. Alas, it also defeats the whole point of energy efficient lighting.
  2. Upgrade the dimmer to a more suitable technology. There are dimmers specifically made for LED control, like Lutron's C-L line but they may be hard to find. Here is one at Home Depot.
  3. Replace the dimmer with a lower wattage capacity in the same technology. This gets the dimmer closer to it designed range. But a cheap one less than 600 watts is hard to find and I bet all your LEDs total less than 50 watts.

Reference: [1]

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up vote 0 down vote accepted

After a little research I discovered that most dimmer switches are "Leading Edge" dimmer switches and that these aren't compatible with LED bulbs and will result in a flicker and reduce the lifetime of the bulbs.

So what I needed was a "Trailing Edge" dimmer switch which I struggled to find in the shops but managed to order online. It was quite a lot more expensive but works perfectly.

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