I've been installing Lutron Caseta dimmers all throughout my house. Everything has been fine except my back porch where I have two lights.

If I only put a bulb in one light, it works fine, dims, etc.

If I put bulbs in both lights, they either flash on and off, or pop and stop working.

Any idea what's going on?

I'm using dimmable LED bulbs for the back porch where I'm having problems. The rest of what I've changed over is built in LED cans.

  • If you stick one incandescent (I know, where do you even find one of those in this day and age) in there, does the other one that's still LED suddenly behave properly? Are the dimmers LED-rated? Commented Sep 25, 2019 at 4:42
  • Does the porch light have a motion detector or a daylight sensor? Those are both items that can cause incompatibilities with dimmers or smart switches.
    – JPhi1618
    Commented Sep 25, 2019 at 14:33
  • Nope. The porch lights are just basic lights.
    – leros
    Commented Sep 25, 2019 at 14:34

2 Answers 2


There's a lot of garbage brands in the LED bulb game, and even if it's not a garbage bulb not all dimmer products are tested against all dimmable LEDs. One of these is likely your problem.

Fortunately, Lutron actually makes known compatibility information pretty easily accessible with a wizard that can be found here: http://www.lutron.com/en-US/Education-Training/Pages/LCE/DimmingCFLsandLEDs.aspx

If you are already using a bulb suggested by that wizard, then I'd start by trying to replace the dimmer with one that was already working inside to rule out a defect in that. If the dimmer is not defective and there's no compatibility problem, it must be either the wiring or the light fixtures themselves.

I've never installed one of those dimmers myself, but Lutron is a generally reliable brand. That's why I'm assuming it's incompatibility. But if you weren't using LEDs out there previously, it makes a wiring issue more likely - LEDs are more sensitive to wiring issues than other bulbs.

  • Interesting. I'm using GE bulbs. I figured those were good. The compatability chart shows a bunch of Philips bulbs and an EcoSmart bulb. I'll try one of those brands as my next step. Thanks!
    – leros
    Commented Sep 25, 2019 at 3:42
  • About five years ago, a batch of GE bulbs I bought had a problem where they'd randomly stop working, but flipping the switch would make them work again. I haven't had a problem with Phillips LEDs yet, beyond that their life expectancy in hours seems to halve if they're constantly on (unlikely to be an issue in a residential application). My front porch light has been a Phillips for ~5yrs now, it's on about 6hrs a day.
    – Nate
    Commented Sep 25, 2019 at 3:51
  • GE should be pretty good stuff. They're the only member of the Phoebus Cartel that still takes responsibility for making their own LEDs; the rest have divested their screw-in-LED business because they see it as having no future. Commented Sep 25, 2019 at 4:44
  • 1
    I got some Philips bulbs and it works just fine now. Thanks!
    – leros
    Commented Sep 28, 2019 at 18:42
  • Good to hear Ieros.
    – Nate
    Commented Sep 29, 2019 at 0:15

100% is the wiring. I had the same problem a couple of months ago with a switch+plug and a switch, sharing all of them one hot wire (???). When you put a bulb in one light... doesn't matter if it's the first or the second light? it works in each one of them? If one bulb works no matter in which light is connected, then (probably) the problem is because of the voltage, and how the wiring has been done. You must understand how the parallel and series circuits work. In a series circuit the voltage is the sum of the voltage of the individual components, in a parallel circuit the voltage is the same for all the elements (basic electronics). So if your line is 120v, and you connect a 120v light, everything runs smoothly, but if you connect 2 lights at 120v (for instance) in a series circuit, you have 2x120v (240v) in a 120v line. The wattage at half voltage is a quarter [Power = (E^2) / R], which means that if your lights runs at 20w (for example), in your case will run at 5w, that's why, when you connect one bulb it works like a charm, and when you connect 2, both of them are popping. That's my guess.

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