Relays & dimmer modules that work with Home Assistant
The invisible option: relay and dimmer modules hide behind your existing UK light switches and sockets, making dumb circuits smart while everything looks completely normal. This is Home Assistant's power-user territory — Shelly's local Wi-Fi modules and no-neutral Zigbee options dominate. Crucial UK caveat: many British back-boxes have no neutral wire, so we flag no-neutral support on every module.
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Frequently asked questions
What does 'no neutral required' mean and why does it matter in the UK?
Most UK lighting circuits wired before the 2000s only bring live and switched-live to the switch — no neutral. A standard relay module needs a neutral to power itself, so for those back-boxes you need a no-neutral module like the Sonoff ZBMINIL2 or a Shelly with a bypass fitted at the fitting. Check behind your switch before ordering anything.
Are Shelly modules better than Sonoff for Home Assistant?
Shelly's headline advantage is its integration: built into Home Assistant core, fully local, with instant push updates and per-module scripting. Sonoff's Zigbee modules (via Zigbee2MQTT) are also excellent and cheaper — the choice usually comes down to whether you'd rather grow a Wi-Fi or Zigbee estate.
Can I legally fit these modules myself in the UK?
Replacing accessories on an existing circuit — which includes fitting a module in a back-box or ceiling rose — is generally not notifiable work in England and Wales, but it must still be done safely and to BS 7671. If you're not confident isolating the circuit and identifying conductors, a qualified electrician will fit a module in under half an hour.