Smart Home Without Neutral with Shelly 1L and 2L Gen 3 and Home Assistant Integration

What Is a No-Neutral Relay and How Does It Work?

Most smart relays need a neutral wire to power their own electronics. However, in many electrical installations (especially in Spain), only the live wire reaches the switches.

The third-generation Shelly 1L and 2L use what’s known as parasitic power. This means they let a minimal amount of electricity pass through the bulb itself to stay powered and connected to Wi-Fi, even when the light is "off".

The Crucial Role of the Shelly Bypass

When using very low-power LED lights, that small flow of electricity can make the bulb flicker or stay faintly lit. To prevent that, Shelly includes the Bypass.

• When is it needed? Only if your bulb’s load is below 20W.
• What does it do? It is installed in parallel with the bulb to divert that parasitic current so the light stays completely off.

Shelly 1L vs Shelly 2L Gen 3: Which One Should You Choose?

Although both devices share the same technology and a super-compact size (just 1.6 cm thick), there are key differences:

1. Shelly 1L Gen 3: Designed to control one circuit (one switch and one bulb). It supports up to 200W.
2. Shelly 2L Gen 3: Allows you to control two independent circuits. In addition, its output 2 (O2) supports up to 700W, giving it extra versatility compared with the 1L model.

Both models work with Wi-Fi and Bluetooth, act as a Bluetooth Proxy (ideal for extending the range of your Home Assistant sensors) and do not require any external hub or controller.

Step-by-Step Installation (No Need to Worry)

IMPORTANT: Before you begin, turn off the power at the breaker panel. Safety comes first.

1. Identify the wires: Locate the live wire and the cable that runs to the bulb.
2. Connect to the Shelly:
   • Insert the live wire into the L input (Line) on the Shelly.
   • Connect the cable that goes to the bulb to output O (Output).
   • Use inputs S1 (and S2 on the 2L) to connect the wires coming from your physical switch.
3. Bypass installation (if needed): You must place it in parallel with the bulb, either at the light fixture itself or in the junction box where the cables going to it come together.

Setup with Shelly Smart Control

Once installed, the pairing process is very easy thanks to Bluetooth:

1. Open the Shelly Smart Control app.
2. Add the device (it will be detected automatically via Bluetooth).
3. Set the button type (switch or push button) and the initial state (on, off, or remember last state).

Home Assistant Integration: Powerful Local Smart Home

One of Shelly’s biggest advantages is how open it is. Integration with Home Assistant is native and local.

• Auto-discovery: Home Assistant will detect the new Shelly as soon as it’s on the same network.
• Full Control: You’ll be able to see the state, control the light, and receive button-press events to create complex automations without relying on the cloud.

Final Thoughts: Is It Worth It?

If you don’t want to, or can’t, run cables through the conduits in your home, the Shelly 1L and 2L Gen 3 are, without a doubt, the best option on the market.

Best of all:

• European build quality (Bulgaria).
• Advanced safety with internal temperature sensors.
• Seamless integration with Home Assistant via local access.

Keep in mind:

• Respect the 200W limit for LED lighting.
• If you have access to the neutral wire in the junction box, it will always be better to use a neutral model (such as Shelly 1PM or 2PM) for greater stability without a Bypass.

Ready to smarten up your home? Don’t forget to use code Hectorzin10 for 10% off on Shelly’s official website!

Have questions about the installation? Leave them in the comments on my latest video and I’ll help you sort them out!

Where to buy

If you are interested in any of the options mentioned, here are the available links:

• Shelly 1L Gen3 — Reviewed in the video (1 Línea): Official store (coupon: Hectorzin10)
• Shelly 2L Gen3 — Reviewed in the video (2 Líneas): Official store (coupon: Hectorzin10)