Shelly
Shelly i4 Gen3
- Native integration
- Local control
- Wi-Fi
- Bluetooth
Prices verified September 2026
See more relays & dimmer modules picks on our Amazon storefront →Our verdict
Not a relay at all — this is an input-only module with 4 dry-contact terminals for turning an existing wall switch or push-button into an HA scene trigger, without ever switching mains load itself. Handy behind a bank of unused gang-switch positions, or for wiring in a doorbell push as an automation trigger. It still needs mains L+N to power itself even though it isn't switching anything. At 37×42×16mm and 19g it hides behind a standard UK backbox, with idle draw under 1W. Being mains-powered rather than battery, it makes a solid always-on BLE proxy: Bluetooth 4.2 lets it relay nearby Shelly BLU buttons and sensors into HA without a dedicated gateway.
What can Home Assistant control on the Shelly i4 Gen3?
| Control | Type | What it does |
|---|---|---|
| Input 1-4 | Binary sensor / event | Four independent dry-contact terminals; a binary sensor if configured as switch mode, or an event entity (single/double/long press) if configured as button mode — mode is set on-device, not in HA. |
| 4-input scene controller | Pattern | Wire 4 unused gang-switch positions into the inputs, set all four to button mode, and map each press event to a distinct HA scene — turns a blank wall plate into a discrete multi-scene controller without adding a dedicated keypad. |
Each of the 4 inputs is independently set to switch or button mode on the device itself, and that per-input choice changes what HA sees: switch mode creates a binary sensor entity with live on/off state, while button mode creates an event entity firing single/double/long/triple press — so an automation built for state changes will silently do nothing if an input is actually left in button mode. Debounce and invert aren't exposed as HA entities at all; they're set once in the Shelly web UI/app, so wiring quirks have to be fixed at the device, not in HA. Unlike the Plus Uni, the i4 Gen3 has no analog/voltage input capability — it's dry-contact only across all 4 terminals, so every input is strictly digital switch or button, never an analog read.
Specs
| note | input/scene-trigger module only — no switched output, no load rating |
|---|---|
| inputs | 4 |
| weight g | 19 |
| dimensions mm | 37 x 42 x 16 |
| relay channels | 0 |
| bluetooth proxy | Bluetooth 4.2 BLE — acts as an always-on gateway relaying nearby Shelly BLU buttons/sensors into HA (range ~10m indoors / 30m outdoors) |
| standby power w | <1 |
| neutral required | true |
How does the Shelly i4 Gen3 compare?
| Product | From | Protocol | Local control | Integration |
|---|---|---|---|---|
| Shelly i4 Gen3 (this product) | £15.49 | Wi-Fi, Bluetooth | Yes | Native |
| Aqara Dual Relay Module T2 | £29.74 | Zigbee | Yes | Zigbee2MQTT / ZHA |
| Aqara Single Switch Module T1 (No Neutral) | £26.99 | Zigbee | Yes | Zigbee2MQTT / ZHA |
| Candeo Zigbee Dimmer Module (C-ZB-DM204) | £39.99 | Zigbee | Yes | Zigbee2MQTT / ZHA |
Frequently asked questions
- Does the Shelly i4 Gen3 work with Home Assistant locally?
- Yes. The Shelly i4 Gen3 is controlled locally in Home Assistant through a built-in Home Assistant core integration (shelly), so it keeps working if your internet connection or the Shelly cloud goes down. Control and state updates stay on your own network.
- Which protocol does the Shelly i4 Gen3 use, and do I need a hub?
- The Shelly i4 Gen3 uses Wi-Fi and Bluetooth. To pair it with Home Assistant you need no hub — it joins your Wi-Fi network directly; or a Bluetooth adapter on your Home Assistant host or an ESPHome Bluetooth proxy. Shelly's own hub is not required when you integrate through a built-in Home Assistant core integration (shelly).
- How much does the Shelly i4 Gen3 cost in the UK?
- The lowest price we have listed for the Shelly i4 Gen3 is £15.49 at Shelly Store UK, with other UK retailers at up to £15.50. Prices were last checked in September 2026 and change often, so confirm on the retailer's page before buying.