HomeHome AutomationOne switch for all your needs? Shelly 1L

One switch for all your needs? Shelly 1L

New device from Shelly

The world is split by different electrical standards, as each country comes up with their own definition of what’s best for its citizens. What if there was a device that caters to both wall light switch wiring standards? Shelly 1L can connect no-neutral wall switches and the ones that come with live and neutral wire inside the in-wall console. Full disclosure, I accepted a bribe from Shelly: one coffee mug, I write about these anyway, but I would look a little more tired than usual. You can sweeten up that deal by topping up my coffee tip jar.

Shelly 1L = L stands for “lite”?

Shelly sent to me another product to take a look at and unlike Shelly 1 (review), Shelly 1PM (review) or even Shelly 2.5 (review) the box felt very small and light. To the point where I started to suspect it was empty. Thankfully, Shelly 1L was inside. The general footprint is the same as the Shelly 2.5, but the connected relay feels lighter and it’s much slimmer. What pleases me even more, it comes with 7 terminals (something I complained about multiple times before).

“lite” – isn’t just about the size. Shelly 1L doesn’t come with the usual 10A load limit, the device can carry 4.1A safely, which is fine if you are automating lights, but it may not be enough for anything else. That’s not the only change, there is more to learn before you can use Shelly 1L.

Shelly 1L specs:
Power supply AC110-230V ±10%, 50/60Hz
Maximum load4.1A (5A for short operation)
Minimum load – no neutral connected, without bypass20W resistive load
Wireless/WiFi Protocol802.11 b/g/n
Size42mm x 36mm x 14 mm

What’s nice to see is the assurance that Shelly 1L will work with pretty much any lights without causing interference or flicker:

  • Incandescent lamps
  • Fluorescent lamps.
  • Halogen lamps.
  • Dimmable LED
  • Non-Dimmable LED
  • Fluorescent tubes
  • Neon lamps.

To bypass or not to bypass, that’s the question

I mentioned, that Shelly 1L caters to both wiring standards. You can use the same device in the control boxes with no-neutral and live & neutral configurations. There is a catch. While the L&N configuration is pretty straightforward, the no-neutral installation comes with additional limits:

  1. min 20W – to use the device as is, your load has to be at least 20W, otherwise, bypass (sold separately) is needed to make the Shelly 1L work with no-neutral circuit
  2. bypass (€2.42) removes the limit of min 20W resistive load, but you will have to install it yourself to make the device work correctly. As the average LED bulb uses 8-10W of power, unless you are automating lights with 2-3 bulbs, the bypass add-on will be mandatory.

Bypass isn’t expensive, but the extra device will increase the complexity of the installation. You can see both installation schematics below:

Eagle-eyed readers will notice that Shelly 1L supports 2 switches. These can be configured independently and set to various modes including push, toggle, and edge. What’s also new are the default power state modes that include the current state of the physical switch 1 and 2. Pretty handy for detecting switch changes made during a power outage.

What’s new in Shelly 1L is how the device is handling switching toggles. Previously, Shelly devices would use mains power to run the switch circuit. Shelly 1L uses 5V logic across Sx and SW1/SW2. Please make sure you don’t connect the mains there by accident.


Shelly 1L isn’t sealed, so I took a peek inside. There is a new layout of the board, and the WiFi chip (probably ESP8266) is covered by a new 5A relay. There is not enough space between the main and the child board to confirm this visually.

At the back of the unit, GPIO pins are also exposed alongside a single push button which can be used to toggle the states and configured in the Shelly app or web interface. There are no dev pads visible on the PCB, but the access to GPIO assures me that you could tinker with the device.

One to rule them all

Once I took a closer look at the schematics, my hopes for the right number of terminals had disappeared. Unfortunately in both scenarios, you will need WAGO-style connectors to complement your wiring style. It’s a shame as a double Sx terminal isn’t needed to split inputs into 2 switches. With a small redesign, Shelly could provide 2 N terminals instead and handle the logic via SW1 and SW2.

While both switches will toggle the same relay, nothing stops you from detaching one of these and using Shelly app/web interface options to toggle another device via web request or MQTT call. A perfect solution if you want to use one wall switch with 2 buttons to control your main light and blinds or bedside lamp connected via a smart plug. I actually did this for my bedroom in this article.


It works as you would expect it to. After all Shelly had enough practice with other switches to nail the L&N performance. The device is very responsive and changes made via a physical switch reflect in the app within a second.


If you connect less than 20W load without the bypass, you will see the light flickering madly, which leads to a factory reset, in other words, don’t do it. Bypass fixes this and normalises the power delivery to the Shelly unit. Once added to the circuit, Shelly 1L acts snappy and responds promptly to web requests and traditional wall toggles.

You are most likely to install the bypass in the ceiling fitting allowing the current to bypass the bulb and deliver electricity to the Shelly device without issues. I came across a similar solution where a smoothing-out capacitor was used to achieve the same effect. For obvious reasons, I would advise you to stick to bypass with Shelly 1L. For peace of my mind, I tested how much electricity the bypass configuration is using: 0.8W.

Fake power meter

In line with other Shelly devices, Shelly 1L will contribute towards the total room power usage, unlike Shelly 1PM and Shelly 2.5, this device isn’t equipped with a power meter, but it can be set to contribute a fixed number of Watts. It’s a neat compromise as if you are running non-dimmable lights, the power consumption of these is usually fixed.

To contribute to the room’s usage, check the power consumption of all bulbs connected to this relay and enter the number in Watts. The app will do the rest and will calculate the estimated consumption based on the operational time.

Shelly Cloud

If this is your first experience with Shelly Cloud you will be very impressed. If you played with other Shelly devices you can skip this paragraph, Shelly Cloud delivers as usual. Shelly 1L continues with great cloud options with Alexa and Google Home integrations. If that’s not enough, Shelly devices spin up their own web server so you can access the device via a web browser and ignore the cloud aspect of the ecosystem. In fact, the web interface mirrors the app settings, supporting all fancy features like the power-up and switch behaviour, max load cut off and more.

In line with other devices, Shelly 1L comes with the usual settings like schedules, simple automation and default behaviour. Where things get interesting is the ability to send REST calls when the state changes – you can use that to let other ecosystems know about the changes. In case REST API isn’t enough you can also access MQTT although you won’t be able to use cloud services.

Get Shelly

Check out other devices from the Shelly series to build your ultimate DIY automation:

As I covered the software previously, I would recommend you check the software sections of Shelly 2.5 and Shelly 1 reviews for more information.

Final thoughts

Once again Shelly delivers an interesting in-use device that many will DIY home automation enthusiasts will love. I’m slightly sour over the number of terminals, but Shelly’s cloud and the ability to use their API without flashing had been always one of my favourite options and strong arguments for opting into Shelly’s ecosystem. Shelly 1L is the least expensive relay from their lineup – so if you haven’t already – give it a go. What do you think about this connected relay? Let me know in this Reddit thread.

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