How to Install a Zigbee Dimmer Switch in a UK Home
Step-by-step instructions for 2-wire and 3-wire installations — with or without a neutral wire.
Installing a Zigbee dimmer switch in a UK home is a straightforward job — most installations take under 15 minutes. This guide covers what tools you need, how to identify your wiring type, and step-by-step instructions for 2-wire and 3-wire setups.
What you will need
- SM323 rotary dimmer or SM309-S module
- Flathead and Phillips screwdrivers
- Non-contact voltage tester
- Short wire link (if wiring SM323 with no neutral)
- Bypass capacitor (recommended if no neutral wire present)
Step 1: Identify your wiring type
After the circuit is switched off, unscrew your existing wall switch and count the wires connected. Two wires = no neutral – the most common UK setup, all Samotech dimmers would work here. Three or more wires = neutral present – optional to connect, improves stability at low wattages.
Step 2: 2-wire installation (no neutral)
- Connect live feed (brown/red) to L.
- Connect switched live (to light fitting) to V (L OUT) .
- If you wire SM323 module, bridge L and N with a short wire link.
- Connect earth wire to the back of the Samotech faceplate if installing SM323 into a dry lining back box.
Step 3: 3-wire installation (neutral present)
- Connect live to L, neutral to N, switched live to V (L OUT).
- No link wire needed between L and N.
Step 4: 2-way wiring
The dimmer replaces one switch. The second position uses a retractive (momentary) push switch. Connect COM to L and strappers to the S terminal as per the dimmer wiring diagram. Any additional light switch is connected in exactly the same manner. You can have as many additional light switches connected to Samotech dimmers as you want.
Step 5: Pairing with your hub
Restore power. Press the reset button 5 times — the lights start flashing to indicate the pairing process has been initiated. Then pair:
- Home Assistant ZHA: Settings → Devices & Services → ZHA → Add Device
- Zigbee2MQTT: Enable Permit Join in the dashboard
- Philips Hue: Settings → My Hue system → Add accessory
Common issues
| Problem | Fix |
|---|---|
| Bulbs flicker at low brightness | Fit bypass capacitor; raise minimum brightness in hub settings; confirm bulbs are dimmable |
| Lights glow faintly at 0% | Fit bypass capacitor or connect neutral wire |
| Device not found during pairing | Press the reset button 5 times; bring hub closer; confirm Permit Join is active |
For more help see our Zigbee dimmer not working — 10 fixes.
Browse Samotech Zigbee dimmers
Wall-mounted rotary dimmers, inline modules, pull cord ceiling dimmers – all with no neutral wire and full Home Assistant compatibility.
