Shelly 1L flickers

I just installed a Shelly 1L to a light. I have the neutral connected and no bypass. The LED bulb flickers.

I thought that this would not be an issue if the neutral is connected or did I mess something up?

As Shelly 1L is dry relay based, it cannot cause power disruption delivery to the bulb. So it means that device itself is powering on/off constantly (you should be able to hear constant clicking and relay is changing state. So to me it looks like your neutral is not neutral, but disconnected wire in the box…Using multimeter please check voltage between load and neutral, is there someting? If not, you need bypass.

The shelly 1L is not dry contact based. Mine is wired like the lower picture, the neutral is connected.

The shelly 1 is the dry contact version.

Do you hear the relay click or are you just seeing the light slightly dim? Asking because I have one of these where the light seems to pulsate a bit, but since the LED lamps are old, I blame them. I do not hear the relay click on mine.

No relay click.

I did discover an ECO mode in the settings that was turned on.
It was added after I update the firmware to the latest.
Turning it off stopped the flicker on one of my lights and greatly reduced it on another.
I swapped some bulbs around to get rid of the flicker on that last one.

So is it possible the bulb was faulty on that last one?

The bulb did not flicker being connected directly to the mains.

That being said, the bulb that went from lots of flickering to just a little is one of the oldest LEDs in my house. It has the large metal base that gets super hot. The bulb that stopped flickering completely is brand new. I believe it uses the new LED filament technology. The entire body of the bulb is glass.

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Yes it is. I have 5 of them installed and all click like hell when changing the state. Even Shelly support advised to knock on device to change the state if contacts gets permanently connected and device cannot switch off (could happen on highly inductive loads like transformers, that causes excessivly hight load at start).
As I said, nature of your problem indicates that at the moment of light is being turned on, there is not enough power to keep shelly up and keep relay closed, So it switches off, supply gets to normal level and it switches on. Perhaps new bulb works better as have lower power consumtion.
Can you connect the flickering bulb to power (at the place where the Shelly is installed) turn it on and check voltage on the bulb against neutral that is connected to Shelly? Does is keep at constant level or drop significantly when bulb is switched on?

Then you misunderstand the meaning of the term “dry contact”.

The shelly 1 is dry contact because the contact voltage is independent of the voltage that powers the control side. For example, the shelly 1 can switch 12V while being powered by 120V. The control side voltage is connected to the L and N terminals. The output connects the I terminal to the O terminal.

The 1L on the other hand shares the output and control voltages. If the input is 120V then the output is 120V. On the 1L the L terminal is the input for both control and output. The O terminal is the output.

The term does not refer to the fact that there are relays inside, it refers to how they are wired.

Unfortunate mistake on my side… Initially I typed dry contact in my first post, then realized that this is not what I meant and tried to replace dry contact with just relay… but did not removed dry from my initial post… (so you are right) and later on I was so fixated on chanhe made, that I was referring to just relay and started unnecessary dispute. :man_facepalming: So your are right, it is not dry contact, but yet it is relay based :wink:

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The 1L is a unique beast because it can run with no neutral. (I had to do a bit of research on this one)

To power the relay a difference in potential must exist. When the light is off there is a difference in potential across the relay contacts. The bulb completes the circuit path back to neutral because the bulb has some small amount of leakage current. This is true for both incandescent and LED bulbs.

When the bulb turns on the story changes. The 1L needs to generate its own difference in potential because it can no longer use the relay contacts. From what I can tell the 1L uses a set of MOSFETS that are in series with the relay contacts. I’ve seen some other designs that use a TRIAC. These devices can be used to momentarily break the current path to generate a difference in potential without opening the relay contacts. (From here there is some educated guesswork) The easiest way to do this would be to break the current path at the voltage zero crossing. Then wait until the internal circuits are charged enough and reconnect the path. With an incandescent bulb, this is easy because the current follows the voltage. With an LED bulb this is a problem because its current is very irregular and has spikes. The LED does not flow current until the external voltage exceeds the internal voltage of its capacitors. This causes a current spike.

Following the zero-cross strategy, it is possible that the 1L holds the circuit open until the spike happens. When the spike happens it fills its capacitors but disrupts the LED circuits enough to make it blink. This is the reason for the bypass. It adds a small resistor in parallel with the bulb. This resistor behaves like a small incandescent bulb allowing charging near the zero-crossing.

All that being said. I’m using a neutral. The bulb should not blink. I’m guessing that in eco mode the relay is still trying to use a “no neutral” strategy. I have one light that I need a bypass for to run in “no neutral” mode. I had to order the bypass and when it arrives I’ll post on what eco vs no eco does.

So I got the Shelly bypass and guess what, it flickers. With eco on or off. The flicker is very uneven and random. It drives me nuts.

What I found a bit strange is that the Shelly bypass has some active circuitry on it. I was expecting some resistors or capacitors.

Going to order a different bypass and see how it works.

Do you know the specs of the light bulb being used and how many total watts the load is?

The bulb is listed as 5W dimmable. There are 5 bulbs in the fixture. That would be 25W in total. These are the new style where the LEDs are in filaments instead of individual chips.

OK. This rules out the minimum load theory then. According to the spec, these have a minimum load of 20W when used without a neutral or bypass.

Have you tried another kind of bulb by any chance?

It does not work the same way with LED bulbs. Without a bypass, it won’t work at all.

Once the breaker panel is turned on the relay comes online and you can communicate with it. The lights will turn on once. When you go to turn the light off you can hear the relay click. The lights drop to half brightness and the relay goes offline. Until you cycle the breaker the relay won’t respond again.

Maybe a defective shelly

Hi! Did you find a solution to the issue? It seems I’m having a similar issue with an outdoor led lamp that has this grid of LEDs in it. It did not seem to work at all without the Shelly bypass but now it seems to be similar issue than what you described. I believe the load is below 20W but I thought the bypass should’ve helped with that.

I had an electician set it up so there’s no neutral in the wall switch where the Shelly 1L is but the bypass is inside the lamp. I’ll look into it further later to see how it is connected now.

Edit: weird, now it works again. Maybe the load is still so low that it can have issues.

Edit2: other one has now been working fine but another similar LED light fixture flickers now even though that one is connected to neutral. Maybe I’ll try adding the bypass to that one as well.

Edit3: OK original one flickers now again. Maybe I need new LED lamps then…