240v LED Strip - Dimmable Challenge


I bought 15m 240v LED strip which comes with a rectifier attached. I’d like to dim the LED strip but as the rectifier converts it from AC to DC my usual route such as the Shelly Dimmer 2 won’t work. I did try this and although I can dim the LED it flickers due to the AC current.

Has anyone managed to dim a 240v DC LED strip with a connected (Wi-Fi, Zwave etc.) dimmer?


I’m sure the leds itself are powered with DC.
Measure the voltage on pins of ledstrip connector.
If it’s 12 or 24V you can use Shelly RGBW2 to control it (plug it in the middle between connector and Led strip).
If it’s other voltage, then you can do that with RGBW2, supported by additional mosfet tranzistors

It’s 240v AC in, then the rectifier converts it to 240v DC to the LED. I’ve done with 240v rather than 12v or 24v due to the length of the LED and I didn’t want voltage drop and adding power at points along the way would have been challenging due to the location.

Actually it’s more like sqrt(2)*240 = 340V DC

(RMS AC to Peak AC).

Which quite frankly is bloody terrifying in a LED strip.

tbh I’m surprised it works with so high voltage. Not that leds work (they are powered with current, not voltage). but hight potential difference between lines in the strip (so very close to each other) is so hight risk of a short

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High voltage LED strips, these are most commonly used in outdoor settings for long runs - out of touch of anyone to prevent potential shock. Great for lighting on hotels/etc accent, can be used on long runs without the DC drop we see on 12-24V DC low voltage systems.

In short, these were not designed to be dimmed but rather to go full power for long runs. The built in rectifier is probably a cheap slap on and you most likely have strobing all the time. Look with the camera on your phone to see if you get the trademark flicker. The only way to try to fix it is wiring on a non-stroboscopic drive power supply. If it’s strobing don’t use it where the lighting is essential, you can get some eye strain even if it is imperceptible.

I’m sure there is a way if you wash out the strobing completely, but I don’t think any of these options would be cheap. Better to get a big 24v driver, size up on wiring using a wire length calculator, and distribute out if you really want to have active dimming.


Here is a good primer on the difference between high and low voltage LED’s.

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The distributor does sell a manual dimmer for these so they can be dimmed (looks like it sits on the AC side). I’m not sure if you’ve looked at the LED’s I’ve linked but they are designed for both indoor an outdoor use.

I could just buy the manual dimmer and then buy a Shelly switch to control on/off via home assistant.

I did see, it didn’t give too much information, don’t know if the rectifier cleans all strobing. You can definitely use these indoors, I just wouldn’t recommend them anywhere you are going to read or use as primary lighting. I still maintain that these definitely should be out of reach so people can’t touch it with that voltage.

I would try the AC dimmer from them, it’s worth a shot.

Thanks @tylas13. I did try the Shelly 2 dimmer and there was heavy strobing/flicker but I didn’t test with the stock power so can’t say if it was like that without the dimmer. Will test tomorrow.

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