LED bulbs on dimmers don't shut all the way off


Senior Member
My solution so far has been to keep at least one incandescent bulb on the circuit. Just wondering if there are other solutions. Most of the bulbs are noted as non-dimmable. I suppose the dimmable bulbs may not have this problem? Some are in ceiling fans so replacing the dimmer circuit isn't as easy as for a wall switch.


The dimmer circuits here were all in the wall switch box. I did have one fan light combo in the old house with the dimming remote controls controller in the fan-light.

Here just replaced (last year 2021) all of the fan / light switches and lamps with dimmable LED lamps. I had two wires going to each of the fan light s. I wrote about my change over to these modded WiFi switches here.

Two endeavors here.

1 - making sure that each fan/light box had two wires going to the switch box. Redid the switch box using wago wire nut compression devices.
The original electrical contractor here wired two loads to each of the fan/light boxes down to the wall switch. I had to wire one in the ceiling that he forgot to do. In the previous house with conduit did run an extra wire in conduit from the wall switch to the ceiling box.
2 - adding a new light kit to each of the fan / lights. Just modernization and the LED bulbs were included.
3 - new WiFi switches modded with Tasmota. Dimming and fan levels work perfectly.

TREATLIFE Smart Ceiling Fan Control and Dimmer Light Switch, Neutral Wire Needed, 2.4Ghz Single Pole Wi-Fi Fan and Light Switch Combo, Works with Alexa, Google Home and SmartThings, Remote Control



Senior Member
It has to do with the fact that the "smart" portion of the switch/bulb has to maintain power in order to work and therefore a very small amount of current is passing through the switch leg at all times. This parasitic power is just enough that it can cause some bulbs to remain lit even when the switch is "off". Most incandescent bulbs require more power than this parasitic supply so they don't appear to produce light (although they are still receiving the parasitic power). Because LED bulbs are more power efficient, they can produce light even at these low power levels. I assume most non-dimmable LED bulbs require a higher current amount before producing light than the parasitic power can provide which is why the majority of them won't produce light while "off" , but a dimming LED bulb will because they will produce light at a much lower current level.
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