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Wiring & switching Shelly troubleshooting

Shelly 1L or 2L light flickers or won't work without neutral

LED lights that flicker, won't switch reliably or don't work at all on a Shelly 1L or 2L Gen3. Most of it comes down to the Bypass, the globes and which output the light is on.

Checked

  • Gen3

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What are you seeing?

Pick the closest match and we'll point you to the fix most likely to sort it.

Go to the fix

Why it happens

The Shelly 1L and 2L Gen3 switch lights where there's no neutral at the switch. Shelly says that for LED lights they need a Bypass fitted at the light, and that even with one, the globes need to draw more than 5 W.

So most flicker on these comes from a missing or wrong Bypass, or too little load on the circuit. The rest is a load the output wasn't made for.

Before you start

These checks are done in the Shelly app, a browser or by reading the globes. Fitting a Bypass, moving a load to another output or changing a fitting is a job for a licensed electrician. Don't open the wall plate.

Quick checks first

Run these checks before moving on to the fixes.

Checklist 0 of 3 checked
Read the LED

Green means the Shelly is on Wi-Fi and the cloud, yellow means Wi-Fi only, and red means it isn't on Wi-Fi. If it's red, start with the Wi-Fi guide, not this one.

Add up the globes

Add the wattage printed on each globe on the circuit. Over 200 W is more than the 1L, or the 2L's O1, can switch.

Check what kind of lights they are

Note whether the globes are LED or incandescent, and whether the fittings are low-voltage downlights with a transformer. The fixes below depend on it.

Fixes, most likely first

Work down the list and stop when it's fixed.

  1. The LED lights have no Bypass

    How to tell. The lights are LED and the switch is a Shelly 1L or 2L wired without neutral. Shelly says a Bypass is required for all LED lights on the 1L, and on the 2L's O1. Incandescent globes don't need one.
    • Check the box for the Bypass

      Shelly packs a Bypass for 1L/2L Gen3 with every 1L and 2L Gen3. If it's still in the box, it was never fitted.

    • Ask an electrician to fit it at the light

      Shelly says it goes next to the light, connected in parallel with it, and it's small enough to sit inside the fitting. On a 2L, it goes on the light wired to O1. Fitting it is wiring work for a licensed electrician.

  2. The globes draw too little, even with the Bypass

    How to tell. The Bypass is fitted but the light still flickers, and the globes on the circuit add up to 5 W or less. Shelly says the Bypass lets the 1L and 2L control globes over 5 W.
    • Use bigger or more globes

      Swap in a higher-wattage LED globe, or put more globes on the same switch, so the circuit draws more than 5 W.

  3. It's the older Bypass, not the Gen3 one

    How to tell. The Bypass fitted is white, or was bought for an older Shelly. Shelly's older Bypass lists the first-generation Shelly 1L and the Dimmer 2, not the Gen3 models. The Gen3 one is the Shelly Bypass for 1L/2L Gen3.
    • Ask an electrician to swap it

      Replace it with the Bypass for 1L/2L Gen3 that came in the Shelly's box. Swapping it is wiring work for a licensed electrician.

  4. The lights use a step-down transformer

    How to tell. The fittings are low-voltage downlights with a transformer in the ceiling. Shelly lists incandescent and LED lights for the 1L and the 2L's O1, without step-down transformers.
    • Ask an electrician about the fittings

      These lights need different fittings, or a Shelly wired with neutral. An electrician can tell you which suits the circuit.

  5. The fan or fluorescent light is on O1

    How to tell. It's a Shelly 2L, the misbehaving load is a fan or a fluorescent light, and it's wired to O1. Shelly lists fans and fluorescent lights for O2 only.
    • Ask an electrician to swap the outputs

      Put the fan or fluorescent light on O2 and an LED or incandescent light on O1. Moving loads between outputs is wiring work for a licensed electrician.

  6. The circuit draws more than the Shelly can switch

    How to tell. The globes add up to more than 200 W on a 1L, or on the 2L's O1. O2 on the 2L takes up to 700 W.
    • Reduce the load or move it

      Take some globes off the circuit or swap them for lower-wattage ones. On a 2L, an electrician can put the bigger load on O2.

On your device

Shelly 2L Gen3 Its two outputs aren't the same
  • Only O1 needs the Bypass

    O1 switches up to 200 W of LED or incandescent lights and needs the Bypass for LED. O2 switches up to 700 W and also takes fans and fluorescent lights.

Shelly 2L Gen3

Frequently asked questions

No. It's made for switches without neutral, but Shelly says LED lights on it need the Bypass for 1L/2L Gen3, which comes in the box.

No. Shelly says the Bypass isn't needed for incandescent lights on the 1L or the 2L's O1.

Hold its button for 10 seconds to factory reset it. Holding it for 5 seconds turns on its access point and Bluetooth for setup instead.

Scripts that help

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