Zigbee Dimmer Module – No neutral, module only

Yes, the SM323 is a trailing-edge dimmer designed for dimmable LED, halogen and incandescent bulbs from 5W to 200W. Some low-wattage LEDs may need a bypass capacitor for stable dimming at low loads, and when used with Live wire only.

Yes, the SM323 uses native Zigbee 3.0 protocol and integrates directly with Home Assistant via ZHA or Zigbee2MQTT. It also works with Hubitat, SmartThings, and any Zigbee 3.0 hub. No cloud account or proprietary hub is required.

No, the SM323 does not require a neutral wire – it works in both no-neutral and conventional installations. In no-neutral wiring, bridge the L and N terminals as shown in the wiring diagram. If a neutral is present at the switch position, connect it normally for the most stable performance.

Yes, the SM323 supports 2-way and intermediate switching when paired with retractive (default config) switches or standard (pre-configured) on/off light switches.

Lights connected to the SM323 can be turned on or off either by rotating the knob or by simply pressing it. If you want to avoid dimming altogether, just use the press action. Note that with non-dimmable bulbs, accidentally rotating the knob can still cause slight flickering, so dimmable bulbs are always preferred where possible.

Samotech faceplates are made of plastic except the Chrome and Brass finishes, which are metal. All knobs are made of high quality aluminium except where the variant name specifically states plastic (for example, "white plastic"). Check the variant you have selected on the product page for the exact material.

Ensure you follow the wiring diagram correctly. If your dimmer is installed without a neutral wire, bridge L and N terminals as indicated in the wiring diagram.

This phenomenon may occur if the dimmer is connected to a very low load. In such instances, the use of a bypass is recommended.

The nut securing the dimmer to the metal faceplate may have been overtightened. Loosen it slightly to allow the knob to press and move freely.

The knob could have been fitted too deeply. Slightly pull the knob for 1-2mm before pushing it gently again.

Most 1 and 3-gang third-party faceplates are compatible. However, we recommend using original Samotech faceplates, as they provide access to the front reset and brightness adjustment buttons.

To reset the dimmer, cycle the power from the consumer unit five times.

First, verify that your bulbs are indeed dimmable. If they are, wiring a bypass could help solve the flickering issue.

The dimmer may have entered Find & Bind mode, which can occasionally be triggered by repeated or unstable power cycling. Standard dimmable bulbs would normally ignore this, however some fixed LED fittings may fail to return to their normal operating state. To exit this mode, switch off power to the module at the consumer unit for a short period and then restore power.

Not via a hardware 2-way circuit. The SM323 doesn't use a master/companion architecture – every SM323 is fully independent, with its own Zigbee radio, processor and dimming stage.

For a hardware 2-way installation, an SM323 at one end can be paired with a standard light switch, dummy on/off dimmer, or retractive (momentary) switch at the other end. Retractive switches work with default settings; standard switches or dummy on/off dimmers require the 2-way mode to be set to Standard.

For a true two-dimmer virtual 2-way using Home Assistant:
The first SM323 is wired to the light fitting as normal. The second SM323 is wired with live and neutral only, no load connected. Because the load output isn't used, the second dimmer can be installed anywhere in the house – in a different room, on a different floor, even on a completely separate circuit. In Home Assistant, apply the Samotech Direct Mirror Pair blueprint to link the two. Both dimmers then control the same light, with on/off state and brightness mirroring in both directions within 200 ms.

This software-mirrored approach is only feasible if you are running Home Assistant.

The SM323 does not include a firmware-level decoupled mode toggle (like some Aqara wall switches or Inovelli's Smart Bulb Mode), but the same functional outcome can be achieved by installation. Wire the SM323 with live and neutral only, no load connected. The dimmer's wall presses and rotation events still fire over Zigbee, but no light is driven from that switch position – Home Assistant or another hub can then route those events to any target.

This pattern delivers the practical benefits people use decoupled / smart bulb mode for:

• Multi-position 2-way circuits without traveler wire – two SM323 dimmers mirrored via the Samotech Direct Mirror Pair blueprint
• Wall control of smart bulbs – the wall position triggers HA automations that command Zigbee smart bulbs directly, so the bulbs always have mains power
• Software-orchestrated lighting – the wall dimmer becomes a programmable input rather than a direct load controller

This pattern only works with Home Assistant or another hub that can react to Zigbee state-change events. Compared to a firmware-toggle decoupled switch, the SM323 sends state-change events rather than dedicated button-press events, but the functional outcome – wall input without local load control – is the same.

Yes. Wire the SM323 with live and neutral only, no load connected, and pair it with the smart bulb(s) in Home Assistant using either the Samotech Direct Mirror Pair blueprint (1 bulb) or the Samotech SM-Series Linked Sync Group blueprint (2 to 5 bulbs).

The smart bulbs stay on their own circuit, always powered at the mains, never switched off at the wall. Pushing the SM323 turns the bulbs on at the SM323's brightness; rotating dims them. App or voice commands on the bulbs propagate back to update the SM323's tracked state, so the wall position never gets out of sync.

This is the practical equivalent of decoupled mode / smart bulb mode on Aqara H1 wall switches or Inovelli Red/Blue dimmers, but with UK-engineered Samotech hardware (no-neutral, trailing-edge MOSFET, BS 7671:2018 aligned, fits standard UK 35 mm back boxes). Compatible bulbs include Philips Hue (via Hue Bridge + HA), IKEA Tradfri, Innr, Aqara LED bulbs, generic Zigbee bulbs via Zigbee2MQTT or ZHA, and Wi-Fi bulbs that expose as standard HA light.* entities.

What mirrors: on/off state and brightness (0–255) mirror in both directions. Colour (RGB) and colour temperature (CCT) do not mirror – the bulb keeps its last colour, which you can set via HA scenes or automations.

This setup only works with Home Assistant. Without HA, the SM323 with no load connected would still work as a Zigbee device but the bulbs wouldn't follow it.

Make sure your Zigbee2MQTT version is 0.2-1 or newer.
To configure your SM323 dimmer module, simply set the External Switch Type to match your switch:

• push_switch – default mode for retractive light switches
• normal_on_off – use this for standard light switches

⚠️ Note: After changing the mode, a power cycle of the SM323 module is required for the changes to take effect.

You can switch between modes at any time to suit your setup.

Once the Samotech ZHA quirk is loaded – either from a Home Assistant Core release that includes zigpy/zha-device-handlers PR #5039 or via the drop-in config/custom_zha_quirks/ file in the meantime – the SM323 exposes an External Switch Type select entity on the device. Set it to match your switch:

• Push_button – default mode for retractive light switches
• Normal_on_off – use this for standard light switches

⚠️ Note: After changing the mode, a power cycle of the SM323 module is required for the changes to take effect.

You can switch between modes at any time to suit your setup.

Yes. The SM323 works with Home Assistant ZHA for on/off and dimming using standard Zigbee 3.0 clusters, no extra setup required. The manufacturer-specific external_switch_type attribute (Momentary, Toggle, 3-way) is exposed through a Samotech ZHA quirk submitted upstream as zigpy/zha-device-handlers PR #5039. Until the quirk merges into upstream and ships with a Home Assistant Core release, you can use the same file as a drop-in by placing it in your config/custom_zha_quirks/ folder. Zigbee2MQTT users have full support out of the box, including external_switch_type, with no quirk needed.