A smart relay (or smart switch module; the in-wall ones are often called mini smart switches) is a small device that makes your existing wiring smart: it goes in the box behind the wall switch, on the DIN rail in the consumer unit or on an appliance cable, and lets you control lights, boiler, pumps or gate from the app and by voice. In this category you'll find WiFi relays, Zigbee relays and Matter models from Sonoff, Tuya and Shelly, including no-neutral and dry contact versions, that work with Alexa, Google Home and, on Matter models, Apple Home. Below is a quick guide to choosing the right one.
Smart relay or smart wall switch?
With a smart relay you keep the switches and plates you already have: the module hides in the box, the switch keeps working and you can also control the light from the app. If you want to replace the wall switch as well, see our smart wall switches.
Which smart relay should you choose?
It depends on where you install it and what it has to control:
Behind the switch, with neutral
Recommended: Sonoff MINI R4 Extreme or its MINI R4M Matter version, the Sonoff MINI-2GS DUO for two lights or the Tuya Mini Smart Switch Matter 16A
Why: They fit in the wall box (the MINI R4 measures 39.5x33x16.8 mm) and the switch keeps working. MINI R4: WiFi with the eWeLink app, 10 A; the MINI R4M is the same with Matter, so it also works with Apple Home. MINI-2GS DUO: two 10 A channels (16 A in total), Matter. Tuya: 16 A, Matter, also works with Apple Home. All models in in-wall smart relays
No neutral in the box
Recommended: Sonoff Zigbee MINI L2 Extreme, the Sonoff MINI-ZB2GS-L DUO for two lights or the Tuya no-neutral WiFi module
Why: They work with just the live wire and the lamp return. The Sonoff models are Zigbee and need a hub; the Tuya uses WiFi with no hub, with 1 to 4 channels. They are designed for lighting: the Tuya handles 10 to 100 W per channel, the MINI-ZB2GS-L needs a minimum load of 3 W
Dry contact: boiler, gate, lock
Recommended: Sonoff MINI-D (WiFi and Matter), Sonoff MINI-ZBD (Zigbee) or the Tuya Zigbee AC/DC dry contact module
Why: They close a voltage-free contact, like a push button: they control the boiler instead of the thermostat, a gate opener or an electric lock. The MINI-D runs on 230 V or 12-48 V and its contact handles up to 24 V and 2 A. More models, including 5 V and up to 32 V, in dry contact and low-voltage relays
In the consumer unit, on DIN rail
Recommended: Sonoff BASIC-1GSP 32A Matter, Sonoff BASIC-ZB1GSP 32A Zigbee or the Tuya WiFi modular switch
Why: They mount on a 35 mm DIN rail next to the breakers. The Sonoff models handle up to 32 A and measure energy use; the Tuya is a 16 A modular switch (also 25 and 40 A) that you switch on and off from the app. See DIN rail smart relays and smart circuit breakers
Several circuits, one module
Recommended: Sonoff Dual R3 (2 channels) or Sonoff 4CH PRO3 (4 channels, also with RF433 remote)
Why: One module controls two or four independent loads; the Dual R3 also measures energy use and can control a roller shutter. All models in multi-channel smart relays
Inline or for heavy loads
Recommended: Sonoff Basic Gen5 (10 A, Matter) or the 30 A WiFi relay module
Why: The Basic connects inline on the cable of a lamp or appliance. The 30 A module (4000 W) handles pumps, water heaters and other heavy loads. See inline smart relays
With energy monitoring
Recommended: Sonoff MINI ONE PM Zigbee 16A or Sonoff POW Elite
Why: They switch the load and measure how much it uses, in real time and as history in the app. To measure without switching, see our energy meters
Shutters, garage and dimmable lights
Recommended: Sonoff MINI-RBS for roller shutters, the Tuya garage door module or the Sonoff MINI-DIM for dimming
Why: In-wall modules built for one job. More models in blind and curtain automation, gate and garage automation and smart dimmers
WiFi, Zigbee or Matter relay?
WiFi
Hub: Not needed: the relay connects to your home router
App: eWeLink for Sonoff, Tuya Smart / Smart Life for Tuya, Shelly for Shelly
Best for: A few modules and quick installation
Zigbee
Hub: Required: for Sonoff a hub such as the Zigbee Bridge Pro, for Tuya a gateway such as the Tuya Multimode; all models in hubs and gateways
Advantages: There are no-neutral models, and every relay strengthens the network of your other Zigbee devices
Best for: Homes with many Zigbee devices
Matter
Hub: You need the ecosystem controller: an Echo for Alexa, a Google Nest speaker or display for Google Home, a HomePod or Apple TV for Apple Home
App: Also works with the manufacturer's app
Best for: Using the same relay with Apple Home, Alexa, Google Home and SmartThings
Before you buy: what to check
- Neutral: with the power off, look in the box or ask an electrician. If there is a neutral (usually the blue wire), any model works; if not, choose a «no neutral» model.
- Current: 10 A is enough for lights and small loads; for heaters, pumps and water heaters choose a 16, 30 or 32 A model and check the power rating on the product sheet.
- 230 V output or dry contact: lights and sockets need a powered output; boilers, gates and locks need a dry contact.
- Space in the box: mini modules measure about 4 x 3.5 x 1.7 cm; if the box is crowded, use a deeper box or a DIN rail model.
- 2.4 GHz WiFi: WiFi relays can't see 5 GHz networks; keep your phone on the 2.4 GHz network during setup.
Smart relay FAQ
Can I keep using my wall switch?
Yes: in-wall modules have an input for your existing switch or push button, so you turn the light on as usual and from the app too. The product sheet tells you which type of switch it accepts.
What is a dry contact relay?
It's a relay that opens and closes a contact without supplying voltage, just like a push button. It's used to control boilers (instead of the room thermostat), gate openers, electric locks and any device with an input for a button or external contact.
Do they work with Alexa, Google Home and Apple Home?
With Alexa and Google Home, yes, by linking the eWeLink, Tuya Smart / Smart Life or Shelly app. For Apple Home, choose a Matter model such as the MINI R4M, MINI-2GS DUO, MINI-D or BASIC-1GSP.
Can I use them with Home Assistant?
Yes: Zigbee relays with a USB dongle such as the Sonoff Dongle Plus MG24 and the ZHA or Zigbee2MQTT integrations, Matter models with the Matter integration, Shelly locally, and Sonoff and Tuya WiFi models with their own integrations. Each product sheet says how it integrates.
Do I need an electrician?
Yes: the relay is wired at 230 V in the box or consumer unit. Have the work done by an electrician, with the power off.
Not sure which relay suits your installation? Write to us with a photo of the box or consumer unit: we'll help you choose.
0 review
