Tutorials

Sonoff and Zigbee: what you can fit yourself and when to call an electrician

Sensors, radiator heads and plugs you can fit yourself. A relay behind a switch is for someone who knows where the neutral is. Prices from a Latvian shop.

May 28, 2026 · NextTek

Short answer: anything that runs on batteries or plugs into a socket you can fit yourself. Sensors, radiator thermostats, smart plugs. Anything that goes behind a switch or into the panel is 230 V work. If you do not know which wire is live and which is neutral, call an electrician.

Why Zigbee, not Wi‑Fi

Sonoff makes both Wi‑Fi and Zigbee devices. Wi‑Fi relays are handy: plug in, add to the eWeLink app, no hub. But on a battery sensor Wi‑Fi drains the battery, and with lots of devices a cheap router starts to struggle.

Zigbee is made for sensors: little power, its own network, and mains-powered devices pass the signal on. The minus is that you need a hub.

Which hub to get

If you only want the Sonoff app, get the ZBBridge Pro. Sonoff.lv sells it for €22.49 in October. The old ZBBridge without Pro does not support newer devices such as the TRVZB radiator thermostat.

If you want everything in one place with IKEA, Shelly and others, take Home Assistant with a Zigbee antenna. Then you do not need the Sonoff app at all. More in the post about Home Assistant.

What you can fit yourself

Fit a radiator thermostat

The TRVZB screws onto a standard M30×1.5 valve, with adapters for others in the box. It spots an open window and shuts the radiator. The Sonoff.lv price in October is €25.57. The radiator needs a thermostatic valve though. Old one-pipe systems often have none, and fitting a valve is a plumber and building manager matter.

Stick on sensors

Door, temperature, motion and leak sensors run on batteries and stick on with tape. Move them until you find the best spot. No drilling.

Plug in a smart plug

Any will do for a lamp, a fan or fairy lights. For a heater or oil radiator, check the maximum load on the box and do not run it through an extension lead.

Where you need an electrician

ZBMini and MINI relays are small and go into the switch box behind a normal switch. That is 230 V. Per the maker's table, most of the Sonoff MINI series relays need a neutral wire. Older homes often have no neutral in the switch box, only the live to the lamp.

The ZBMini-L2 works without a neutral. With conditions: 6 A maximum, at least 3 W of lamp, not for dimmable bulbs or inductive loads. If an LED flickers after fitting, this is often why.

In Latvia, building wiring is installed under a certified construction specialist, and measurements are made by a certified electrical specialist (LBN 261-15, point 55). The owner is responsible for fire safety at home. If something overheats after your work, that is on you.

A NextTek electrician fits the relay, checks the neutral and sets it up so the switch works without internet. More on the electrician page.

What is new from Sonoff in 2026

At IFA 2026 in September, Sonoff showed the TRV Gen2 radiator thermostat, about 38% smaller and aware of whether anyone is in the room. Also the Presence Core 24G sensor with mmWave radar and seven zones, and the SenseGuard siren up to 105 dB with a backup battery. Check whether they are in Latvian shops before you plan around them.

Sources: sonoff.lv (ZBBridge Pro, TRVZB, ZBMini-L2), Sonoff MINI series, LBN 261-15. Prices checked in October 2026.

Common questions

Does Sonoff work without internet?

Zigbee devices with a local hub or Home Assistant keep working without internet. Wi‑Fi relays with eWeLink run many features through the cloud, so without internet only the switch is left.

What is a neutral wire and why do relays need it?

The neutral is the second wire that closes the circuit. A relay needs power itself, so it wants both live and neutral. Older homes often have only the live in the switch box.

Does the ZBMini-L2 suit any lamp?

No. The maker says at least 3 W, 6 A maximum, not for dimmable bulbs or inductive loads. Very low-power LEDs can flicker with it.

Will the TRVZB fit my radiator?

If the radiator has a thermostatic valve with an M30×1.5 thread, yes, and the box has adapters for other valves. If there is no valve, talk to a plumber and the building manager first.

Which hub does the TRVZB need?

A ZBBridge Pro or another Zigbee 3.0 hub, including Home Assistant with a Zigbee antenna. The old ZBBridge without Pro does not support it, as sonoff.lv also notes.

Why does a sensor drop off the network?

Most often it is too far from the hub. Mains-powered devices such as relays and plugs make a Zigbee network stronger. Put one in between and contact usually comes back.

May I fit a relay in the switch box myself?

That is 230 V work. If you do not know where live and neutral are, and which breaker to switch off, do not do it yourself. The owner is responsible for fire safety at home.

Wi‑Fi or Zigbee, which should I buy?

For one relay or plug, Wi‑Fi is simpler. If you plan more than a couple of devices or battery sensors, take Zigbee and one hub from the start.

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