Shelly 1l Gen4 – Relay module, single-circuit, phase-only, Wi-Fi, Bluetooth, Zigbee, Matter (S4SW-0A1X1EUL)

The Shelly 1L Gen4 is a single-channel, in-wall relay module designed for switching 220–240 V AC lighting circuits. It supports a maximum switching power of 200 W and can be installed without a neutral wire. For LED loads, the included Shelly Bypass is required; with incandescent loads, the device may operate without a bypass.

The module features two external switch inputs marked S1 and S2. It supports Wi-Fi, Bluetooth and Zigbee communication and is also Matter-compatible. The manufacturer specifies Matter as the default profile, which can be switched to a Zigbee profile using the physical button on the device.

The Shelly 1L Gen4 also features a local web interface, MQTT support, webhooks, scripting and KNXnet/IP integration. Its built-in temperature sensor is used for overtemperature protection, and the device also supports overcurrent protection.

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 be powered and used to control lighting or other compatible loads without a neutral wire, using only the live conductor.
• No minimum load: When the Shelly Bypass is installed in parallel with the lighting load, no minimum load is required.
• Wi-Fi connectivity: The Shelly 1L Gen4 connects to the home Wi-Fi network and can be controlled remotely through the Shelly mobile app or other compatible smart home platforms.
• Zigbee connectivity: The Shelly 1L Gen4 can connect to a Zigbee network and be controlled from a compatible smart home platform.
• Matter connectivity: The Shelly 1L Gen4 can be connected to compatible smart home platforms via Matter and controlled remotely through the selected system.
• Remote control: The connected device or load can be controlled remotely over the internet from a smartphone or tablet using the Shelly app.
• Voice control: When integrated with Amazon Alexa or Google Assistant, the connected load can also be controlled using voice commands.
• Schedules and automations: Schedules and automations can be configured. For example, lighting can be switched on and off automatically at specified times.
• Compatibility: The device is designed and tested for use with various lighting loads. The product family supports 110–240 V AC mains voltage.
• Compact design: Its small size allows installation in an electrical wall box or behind a wall switch.
• Protection: Features a built-in temperature sensor for overtemperature protection.
• Local and remote access: The device can be controlled both from the local Wi-Fi network and remotely over the internet.
• OTA firmware updates: Firmware can be updated wirelessly via OTA updates.
• Smart home integration: Compatible with multiple smart home systems and integration methods, including MQTT and Home Assistant.
• New features compared with the previous Shelly 1L: Support for scripting, HTTPS, MQTTS, incoming and outgoing WebSocket connections, Matter and Zigbee communication.

Smart home protocols and platform compatibility

• Wi-Fi: 2.4 GHz connection 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 can be integrated into a suitable Matter system.
• Shelly Smart Control: When using Wi-Fi, the device can be controlled through Shelly's own app and cloud platform.
• 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.

Smart features

• Remote switching: The relay can be controlled from the local network or through a supported smart home system.
• 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 also available through a web browser.
• OTA firmware updates: Firmware can be updated wirelessly.
• Profile switching: The device can be switched from the Matter profile to the Zigbee profile using the physical button.
• Overtemperature protection: The built-in temperature sensor monitors the internal temperature of the device.
• Overcurrent protection: The manufacturer specifies an overcurrent protection function.

Electrical features

• Supply voltage: 220–240 V AC, 50 Hz.
• Number of outputs: 1 relay output.
• Maximum switching voltage: 240 V AC, 50 Hz.
• Maximum switching power: 200 W.
• Neutral wire: Not required.
• Switch inputs: 2, marked S1 and S2.
• Switch signal output: Sx.
• 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.
• Supported loads: Incandescent lamps and LED lamps, without step-down transformers for low-voltage lighting.

Technical specifications

• Product name: Shelly 1L Gen4
• Model: S4SW-0A1X1EUL
• Dimensions: 41.2 × 42.2 × 16 mm
• Net weight: 29 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, 50 Hz
• Maximum switching power: 200 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.
• Bypass for LED loads: According to the manufacturer's specification, the Shelly Bypass must be installed in parallel with the output load when using LED lamps.
• Incandescent loads: According to the manufacturer, the device may operate without a bypass when used with incandescent lamps.
• 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 1L generation, this model adds scripting, HTTPS, MQTTS, incoming and outgoing WebSocket support, Matter and Zigbee connectivity.