Shelly 2L Gen4 – Relay module, two-circuit, phase-only, Wi-Fi, Bluetooth, Zigbee, Matter (S4SW-0A2X4EUL)

The Shelly 2L Gen4 is a dual-channel, in-wall relay module designed for switching two separate lighting circuits or other compatible loads. It operates on a 220–240 V AC, 50 Hz mains supply without a neutral wire. The O1 output supports a maximum switching power of 200 W, while the O2 output supports up to 700 W.

The module features two separate switch inputs marked S1 and S2. The included Shelly Bypass for 1L/2L can be installed in parallel with the load connected to the O1 output and is required for LED lighting. According to the manufacturer, incandescent loads may operate without a bypass.

The Shelly 2L Gen4 supports Wi-Fi, Bluetooth and Zigbee communication and is also Matter-compatible. Its default profile is Matter, which can be switched to a Zigbee profile using the physical button. MQTT, scripting, webhooks, WebSocket and KNXnet/IP are also available for local integration.

About Shelly

Shelly manufactures smart home devices, in-wall and DIN rail-mounted relay modules, energy meters, dimmers, smart plugs, sensors, wall controllers and other building automation devices.

Depending on the model, Shelly products use Wi-Fi, Bluetooth, Zigbee, Matter and Z-Wave communication. In addition to the Shelly Smart Control platform, many devices can also be integrated with Home Assistant, MQTT, KNXnet/IP and other local or cloud-based systems.

Key product features

• No-neutral installation: The device can operate without a neutral connection, using the live conductor for power.
• Two channels: Two separate lighting circuits or other compatible loads can be switched independently.
• No minimum load: When using the included Shelly Bypass for 1L/2L with LED lighting, no minimum load is required.
• Wi-Fi connectivity: The Shelly 2L Gen4 can connect to the home Wi-Fi network and be controlled through the Shelly Smart Control app or a compatible smart home system.
• Zigbee connectivity: The device can be integrated into a Zigbee network and controlled from a compatible Zigbee system.
• Matter connectivity: It can be integrated into a Matter-compatible smart home system.
• Remote control: The two outputs can be controlled independently over the internet through the Shelly app.
• Voice control: When integrated with Amazon Alexa or Google Assistant, the connected loads can also be switched using voice commands.
• Schedules and automations: Schedules, scenes and automations can be configured for both outputs.
• Compatibility: The device is designed and tested for use with various lighting loads. The product family supports 110–240 V AC mains voltage; the 110 V version requires a different Shelly Bypass.
• Compact design: The 41.2 × 42.2 × 16 mm enclosure can be installed in a flush-mounted electrical box or behind a wall switch.
• Overtemperature protection: The internal temperature sensor can be used to protect the device against overheating.
• Local and remote access: When using Wi-Fi, the device can be controlled from the local network or remotely over the internet.
• OTA firmware updates: Firmware can be updated wirelessly via OTA updates.
• Smart home integration: Can be integrated with MQTT, Home Assistant and other compatible smart home systems.
• Gen4 features: Supports scripting, HTTPS, MQTTS, incoming and outgoing WebSocket connections, Matter and Zigbee communication.

Smart home protocols and platform compatibility

• Wi-Fi: 2.4 GHz Wi-Fi communication using the IEEE 802.11 b/g/n standard.
• Bluetooth: Bluetooth 4.2 connectivity.
• Zigbee: IEEE 802.15.4-based communication with Zigbee repeater functionality.
• Matter: The device is Matter-compatible and starts in Matter profile by default.
• Shelly Smart Control: When using Wi-Fi, the two outputs can be controlled independently through the Shelly app.
• Amazon Alexa: ON/OFF control is supported.
• Google Home: ON/OFF control is supported.
• Samsung SmartThings: Can be integrated as a switch.
• Home Assistant: Can be used through Shelly's local integrations or via MQTT.
• MQTT: Native MQTT support is included.
• KNXnet/IP: IP-based integration with KNX systems is supported.
• Wi-Fi range extender: In Wi-Fi mode, the device can be used to extend network access for other Shelly devices.
• Bluetooth gateway: Can forward data from compatible Shelly Bluetooth devices to the Wi-Fi network.

Smart features

• Two independently controllable outputs: The O1 and O2 outputs can be switched independently.
• Local control: Both outputs can also be controlled from the device's local web interface.
• Remote control: When using Wi-Fi and Shelly Smart Control, the outputs can be switched remotely over the internet.
• Schedules: Up to 20 schedules can be configured.
• Webhooks: Up to 20 webhooks can be used, with up to 5 URLs per webhook.
• Scripting: Custom Shelly Scripts are supported.
• Local web interface: Device configuration and control are accessible through a web browser.
• OTA firmware updates: Firmware can be updated wirelessly.
• Profile switching: Pressing the device button five times switches it from the Matter profile to the Zigbee profile.
• Zigbee pairing: After switching to the Zigbee profile, the device enters pairing mode for three minutes.
• KVS: A built-in Key-Value Store is available for storing scripts and local configuration data.
• UDP: UDP communication is supported.
• Encrypted communication: The firmware supports encrypted communication options.

Electrical features

• Supply voltage: 220–240 V AC, 50 Hz.
• Number of outputs: 2 relay outputs, O1 and O2.
• Maximum switching power of O1: 200 W.
• Maximum switching power of O2: 700 W.
• Maximum switching voltage: 240 V AC.
• Neutral wire: Not required for operation.
• Switch inputs: 2, marked S1 and S2.
• Switch signal output: Sx.
• Shelly Bypass: The package includes the Shelly Bypass for 1L/2L.
• Bypass wiring: For LED lighting, the bypass must be connected in parallel with the load connected to the O1 output.
• Incandescent loads: According to the manufacturer, the O1 output may be used without a bypass with incandescent lamps.
• Supported O1 loads: Incandescent lamps and LED lamps, without step-down transformers used for low-voltage lighting.
• Supported O2 loads: Incandescent lamps, LED lamps, fluorescent loads and fans.
• Power consumption: Less than 1.2 W.
• External protection: A 10 A protective device with B or C tripping characteristics, 6 kA breaking capacity and energy-limiting class 3 is required.
• Overtemperature protection: The device uses an internal temperature sensor to detect overheating.
• Overcurrent protection: The manufacturer's documentation also specifies an overcurrent protection function.

Technical specifications

• Product name: Shelly 2L Gen4
• Model: S4SW-0A2X4EUL
• Dimensions: 41.2 × 42.2 × 16 mm
• Net weight: 30 g
• Maximum terminal tightening torque: 0.4 Nm
• Wire cross-section: 0.5–4 mm², solid, stranded or ferruled conductors
• Wire stripping length: 6–7 mm
• Installation: In-wall, in a flush-mounted electrical box
• Housing material: Plastic
• Housing colour: Cyan
• Terminal colour: Grey
• Operating temperature: -20 °C to +40 °C
• Operating humidity: 30–70% relative humidity
• Maximum operating altitude: 2000 m
• Power supply: 220–240 V AC, 50 Hz
• Shelly Bypass: Included in the package
• Power consumption: <1.2 W
• Neutral required: No
• Maximum switching voltage: 240 V AC
• Maximum switching power of O1: 200 W
• Maximum switching power of O2: 700 W
• Internal temperature sensor: Yes
• Wi-Fi: IEEE 802.11 b/g/n
• Wi-Fi frequency range: 2401–2483 MHz
• Maximum Wi-Fi RF power: <20 dBm
• Wi-Fi range: Up to 30 m indoors and 50 m outdoors, depending on environmental conditions
• Bluetooth: 4.2
• Bluetooth frequency range: 2402–2480 MHz
• Maximum Bluetooth RF power: <4 dBm
• Bluetooth range: Up to 10 m indoors and 30 m outdoors, depending on environmental conditions
• Zigbee: IEEE 802.15.4
• Zigbee repeater: Yes
• Zigbee frequency range: 2405–2480 MHz
• Zigbee range: Up to 100 m indoors and 300 m outdoors, depending on environmental conditions
• CPU: ESP-Shelly-C68F
• Flash memory: 8 MB
• Schedules: 20
• Webhooks: 20, with up to 5 URLs per webhook
• Scripting: Yes
• MQTT: Yes
• Encryption: Yes
• UDP: Yes
• KVS: Yes

Additional features

• Flush-mounted design: The 41.2 × 42.2 × 16 mm module can be installed in a standard electrical wall box or behind a wall switch.
• Different load capacities for O1 and O2: The O1 output supports a maximum switching power of 200 W, while O2 supports up to 700 W, so the electrical load capacity of the two channels is not identical.
• Bypass location: The included Shelly Bypass for 1L/2L is connected in parallel with the load on the O1 output.
• LED loads: A bypass is required when using LED lighting on the O1 output.
• Profile switching: Pressing the device button five times switches it from the Matter profile to the Zigbee profile.
• Gen4 features: Compared with the previous Shelly 2L generation, this model adds Zigbee, Matter, scripting, HTTPS, MQTTS, and incoming and outgoing WebSocket support.