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We have a Lutron Caseta dimmer switch which controls a set of four downlights.

I tried replacing the bulbs with Hue downlights (knowing full well that these wouldn't play well with the dimmer, except perhaps at maximum brightness), and observed the following behaviour:

  • None of the lights would receive power when all four downlights were smart bulbs.
  • The lights would all receive power if three downlights were smart bulbs, and one downlight was the original regular downlight. However, in this state:
    • The smart bulbs pair and operate properly, except that:
    • If the smart bulb's app-based dimmer was set to below 50% brightness, then all the bulbs, including the regular bulb, would turn off completely instead, then all four bulbs would turn back on again about two seconds later.

What could be causing the app-based dimmer to cause the entire circuit of lights, including the regular bulb, to briefly turn off then on again?

Machavity
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jogloran
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1 Answers1

32

You're looking at the problem upside down. You are thinking the smart bulbs are causing it. Actually, the Lutron Caseta dimmer is causing it.

The smart bulbs are behaving normally, however their normal behavior is breaking the dimmer.

The dimmer can't deal with four smart bulbs downline of it because (very typically) the dimmer doesn't have a neutral and needs to pass current through the bulbs at all times. The Hue bulbs aren't cooperating with that, that's why it needs one plain bulb still present. This is stock advice we give around here when someone tries to put n LED bulbs on a dimmer (try changing 1 back to incandescent; success = incompatible dimmer).

When you set the smart bulbs below 50% brightness, again there is now too little current going through them for the Caseta dimmer to function.

You knew this wasn't going to work. Convert the Caseta to a plain switch and don't look back.

Hey, free dimmer! :)

Harper - Reinstate Monica
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