The Shelly Dimmer 2 is a smart WiFi dimmer that allows you to wirelessly control and dim your lights via an app, voice assistant, or automation platform like Home Assistant. Thanks to its compact design, it fits behind an existing wall switch and even works without a neutral wire. In this guide, we’ll walk you through how to install and configure the Shelly Dimmer 2 for optimal performance.
What you need for installation
Before you start, make sure you have the following items:
Shelly Dimmer 2 module
Screwdriver and voltage tester
Wall box (at least 50 mm deep is recommended)
Smartphone with the Shelly app (iOS or Android)
WiFi network (2.4 GHz)
Dimmable LED or halogen lights
Optional: momentary or toggle wall switch
The Shelly Dimmer 2 supports both installations with and without a neutral wire. If you don’t have a neutral wire, make sure your connected load is at least 20W, or use the optional Shelly Bypass.
Wiring diagram and connections
The module has the following terminals:
L: Line input (live, brown)
N: Neutral (blue, optional)
O: Output to light
SW1: Switch input 1 (main switch)
SW2: Switch input 2 (optional scene or second switch)
Installation with neutral wire:
Connect the brown live wire to terminal L
Connect the blue neutral wire to terminal N
Connect the wire going to the light to terminal O
Connect the switch to SW1 (and optionally SW2)
Installation without neutral wire: Leave N unconnected, ensure at least 20W of load or install a Shelly Bypass across the light fixture.
Power on and initial setup
Once the wiring is complete, place the Shelly Dimmer 2 behind your wall switch inside the electrical box. Turn the power back on from your circuit breaker.
Setup via the Shelly app:
Open the Shelly app and select “Add device”
Connect to the Shelly’s temporary WiFi network (SSID starts with “ShellyDimmer-xxxx”)
Select your home WiFi network and enter the password
Once connected, you can name your device, assign it to a room, and configure settings
From the app, you can configure options such as:
Minimum and maximum brightness levels
Switch type (momentary, toggle, edge)
Dim rate and transition effects
Default state after power loss
Integration with Alexa, Google Assistant, MQTT, or Home Assistant
Common mistakes and useful tips
To ensure proper operation, keep the following in mind:
Use only dimmable bulbs: Non-dimmable LEDs can flicker or malfunction
No neutral + low load: Use a Shelly Bypass or increase the load to at least 20W
Calibrate properly: Run the automatic calibration via the app after installation
Weak WiFi signal: Install the module close to your router or use a repeater
Not enough space: Use a deeper wall box or extension frame if needed
The Shelly Dimmer 2 is a powerful and flexible solution for smart lighting. With its support for installations with or without a neutral wire, wide compatibility with different switch types, and control through the Shelly app or voice assistants, it’s a great choice for modern smart homes without the need for a separate hub.
