No Neutral, No Problem: A Closer Look at the Aqara T1 Switch Module with ZHA & Zigbee2MQTT
The T1 (in wall) Switch Module is another well-made Zigbee device from Aqara that is part of the same product line as others that I have tested (thermostat, smart plug, switch, mini switch). The device works with both ZHA and Zigbee2mqtt although not all of the functionality from the official app is supported.
What is the T1 switch module about?
The T1 switch module is an in-wall smart relay that works similar to the full H1 Aqara switch I tested before. The difference here is that you do not need to replace the whole switch but can instead keep (at least the face plate of) the switch.
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Aqara T1 switch module (no neutral)
Aqara T1 switch module (neutral)
Aqara H1 switch (no neutral)
Shelly 1 Wifi alternative
One notable aspect of the Aqara T1 Switch non-neutral module I tested is that it doesn’t require a neutral wire, which can be a significant advantage in some -older – installations. However, it’s worth noting that this comes with some downsides too: the devices does not offer power measurement features and is an end device, which means it doesn’t function as a Zigbee router that extends your existing network. If you want to avoid that and have neutral wires available you can also get another version that supports the additional connection.
The Aqara T1 Switch Module uses the usual white plastic from Aqara devices that feels quite premium. It has four connections – 2 for connecting the existing switch, one hot and one ground wire as well as a single input button and an external antenna. The button can be used to toggle the output and put the device in pairing mode by pressing it for a couple of seconds.
The external antenna is quite neat. While the device itself is quite small (around 4,2x4x2cm) and is usually placed behind the light switch the antenna is another small “paddle” connected via a single wire. This way it can be placed under the switch cover thus providing a better connection without interference from the high voltage wires and the metal in the switch (cover).
Using the T1 switch module with ZHA
The module pairs with ZHA quite easily. Put ZHA in pairing mode by going to Integrations – ZHA – configure – add device and press the single button the switch for a couple seconds until the LED starts blinking rapidly. Shortly afterwards a new devices should show up in Home Assistant.
The Aqara T1 Switch Module shows up in ZHA with a single switch and temperature entity. Unfortunately that one is not working and always shows 0.2°C – a know problem from other Aqara devices used with ZHA. This may be a minor inconvenience for some users, but it doesn’t affect the primary function of the device – it reacts quickly to toggling the switch – virtual and physical – but with a slight click of the relay.
Using the T1 switch module with Zigbee2MQTT
Integrating the switch with Zigbee2MQTT is similarly easy. Click the allow new devices button in the Zigbee2MQTT and put the switch in pairing mode via the single button. It shows up right afterwards and supports the same switch as ZHA but also provides a couple of additional details.
Via Zigbee2MQTT you can also set up the power outage memory (after power outage should it remember the last state?) and change the switch type. This way the module can be used with toggle and momentary type of switches. The device temperature is not shown here either though.
How good is it?
Overall, the Aqara T1 Switch Module is a well-designed and reliable (as far as I could test it) Zigbee device that offers some useful features. The external antenna is a pretty cool idea that might severely increase the range in some cases and the small size allows it to be used even in old installations. While it may not be the best choice for all users, it is certainly worth considering for those who require a switch module without a neutral wire. However, it’s important to keep in mind that the device is only a Zigbee end device and doesn’t function as a router.
There are some very interesting alternatives out there, like the Wifi based Shelly devices but if you are looking to build a Zigbee network and keep your existing light switches then the T1 switch module might just be the right devices for you.