Shelly
Shelly i4 Gen3
- Wi-Fi
- Bluetooth
Verified September 2026
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.
In Home Assistant
| 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