Silent Pull Cord Switch UK – Zigbee Smart Ceiling Dimmer (Home Assistant)

Description

A silent Zigbee pull cord dimmer that mounts inside the ceiling rose of an existing pull-cord light fitting. Replaces the standard plastic ceiling rose with a smart unit that adds dimming, voice control, and full local automation to any pull-cord lighting circuit – without needing a wall switch position, neutral wire, or proprietary hub.

Native Zigbee 3.0 device. Pairs with Home Assistant (Zigbee2MQTT or ZHA), SmartThings, Hubitat, Philips Hue Bridge, Aqara Hub M2, and any other Zigbee 3.0 coordinator. Voice control via Alexa, Google Assistant, and Apple HomeKit through your hub’s bridge integration. For no-hub setups with Alexa or Google direct, see the WiFi version (SM325WF).

Why “silent” matters

Traditional pull-cord switches use a mechanical toggle that makes a loud “click” every time the cord is pulled. In a quiet room – especially a bathroom at night – that click is jarring. It’s also a clear signal to anyone in the next room that someone is up and about, which becomes annoying in flats and shared houses.

This pull cord switch uses a solid-state electronic switching mechanism rather than a mechanical relay. Pulling the cord triggers an electronic on/off transition with no audible click. The only sound is the soft fabric noise of the cord itself. Genuinely silent operation.

How the dimming works

A standard short pull toggles the light on or off, like any pull-cord switch. Pull and hold the cord, and the brightness ramps smoothly up or down. Release when you reach the level you want.

The direction alternates with each hold – first hold ramps up, next hold ramps down – so you can quickly find a comfortable level without needing a separate dimmer dial or app. The current brightness is remembered when you switch the light off and on again with a short pull.

For dimming to work, the connected bulb must be dimmable. Standard non-dimmable LEDs will flicker or fail to switch on properly when this dimmer is active. We recommend using dimmable LED bulbs rated for trailing-edge dimming.

Why Zigbee over WiFi for this product

Both this (SM325ZG) and the SM325WF WiFi version do the same physical job. The Zigbee version is the better fit if:

• You run Home Assistant or any local-first smart home. Zigbee gives you fully local control – no cloud dependency, no internet outage breaks your bathroom light.
• You have a Zigbee hub already (Hue Bridge, SmartThings, Hubitat, etc.). One more Zigbee device on the mesh strengthens the network.
• You want fast response. Zigbee commands take 100-300ms locally versus 1-3 seconds for cloud-routed WiFi commands.
• You have many smart devices. Zigbee meshes scale to hundreds of devices without congesting your router.

Pick the WiFi version (SM325WF) instead if you don’t run a hub and just want Alexa or Google direct.

Where to use it

The ceiling rose form factor solves a specific UK lighting problem: rooms where there is no convenient wall switch position.

• Bathrooms – UK wiring regulations require switches outside the room or pull-cord style for safety. This adds smart control without modifying the wiring.
• Lofts and attics – often have a single ceiling rose with a pull cord and no wall switch. Adds dimming and voice control without re-wiring.
• Bedrooms with no bedside switching – install in the ceiling rose to add dimming you can operate from the cord, an Alexa command, or your phone.
• Older properties with surface-mounted ceiling fittings where adding a wall switch would mean lifting floorboards.
• Walk-in cupboards and pantries with a single bare-bulb fitting.

Installation replaces the existing ceiling rose. No additional wiring, no neutral required beyond the standard ceiling-rose wiring, no wall plastering. Most installs take 15-20 minutes for a competent DIY-er.

Hub compatibility

Generic Zigbee 3.0 device using the standard Level Control and OnOff clusters. Works with any Zigbee 3.0 coordinator:

• Home Assistant (Zigbee2MQTT or ZHA) – fully local. Recognised as a generic Zigbee dimmer with on/off and brightness controls. All standard automations work.
• Philips Hue Bridge – paired as a third-party Zigbee 3.0 device. Appears in the Hue app for routines and scenes.
• SmartThings – paired via the Generic Zigbee Dimmer driver.
• Hubitat – built-in driver supports on/off and brightness locally.
• Aqara Hub M2 / G3 – works as a third-party Zigbee device.
• Amazon Echo Plus / Echo Hub – pairs directly to any Echo with a built-in Zigbee radio for Alexa routines.

Voice control via Alexa, Google and HomeKit

Once paired to a hub, voice control works through whichever assistant your hub bridges to. Commands like “Alexa, dim the bathroom light to 30 percent” or “Hey Google, lights off” work as expected. The switch reports state back to the hub so the assistant always shows the correct on/off status, even if the physical cord has been pulled.

Installation overview

Standard ceiling-rose replacement. The original ceiling rose is unscrewed from the ceiling, wiring is transferred to the new smart unit’s terminals (live, switched live to fitting, earth – the standard pull-cord setup), then the new ceiling rose is secured. No neutral connection needed beyond what your existing pull-cord wiring already provides.

Safety: Always isolate the circuit at the consumer unit before working on mains wiring. If you are not confident with mains electrical work, use a qualified electrician. UK regulations classify ceiling rose replacement as notifiable work in some circumstances; check Part P requirements for your specific situation.

Specifications

What’s in the box

• 1 × Zigbee smart pull-cord ceiling rose dimmer (SM325ZG)
• 1 × Pull cord (standard length, replacement)
• 1 × Mounting screws
• 1 × Wiring diagram

Dimmable LED bulbs and additional pull cord lengths/colours are sold separately. See our vintage style replacement pull cords range for cord upgrades.