Zigbee Relay Review – Aeotec Pico Switch & Pico Duo Switch

I have been on a smart lighting and smart relay installation spree in my new home. So far I have got the Wi-Fi Shelly 1PM, Shelly 2.5, and the Z-Wave based Shelly Qubino Wave 1PM set up in Home Assistant. So what’s missing? Zigbee relays!

I have been using Zigbee devices such as Sonoff sensors & Ikea Tradfri bulbs in my home. So I was happy to receive retail samples of the brand new Aeotec Pico and Pico Duo Zigbee relays from Aeotec for this review.

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How to use this Smart Relay

Since my home already has dumb switches and (mostly) dumb ceiling lights that I do not want to replace, it made sense for me to retrofit my existing dumb switches to make them smart.

Installing a smart relay behind an existing switch or power socket in the wall is a good choice for when you want to keep your existing physical switch or socket but want to remotely control or measure an electrical load (light/fan etc.) connected to that switch.

This way you can control the connected load through the physical switch as well as remotely through the smart relay using Home Assistant or any other Zigbee compatible smart home platform.

Since the Aeotec Pico and Pico Duo switches work as Zigbee repeaters, I will be using it to strategically extend the wireless range of my Zigbee network as well. Just like Z-Wave, only mains powered Zigbee devices are capable of being repeaters, so an in-wall relay is a great fit for this purpose.

As usual, I will be using these smart relays together with Sonoff Zigbee motion sensor for motion-activated lighting. The idea is that Home Assistant will turn on the lights through the relay whenever motion is detected and after some time switch them off. Of course if anyone wants to turn on the lights physically, the existing physical switch will continue to function exactly as it always has. But I also then have the added bonus of Home Assistant being aware fo the status of the switch and turn off the relay if someone forgets to turn the lights off! I can also use it as part of my night mode routine to ensure all lights are off at bedtime.

What’s in the box

The Pico Switch and Pico Duo Switch have similar packaging.

The box contents are similar as well:

• Pico Switch
• 2x WAGO clamps
• 1x DIN Rail Mount
• User manual & Safety information

Specifications of the Aeotec Pico Switch

Physical Design

Visually both the Pico and Pico Duo Switch look identical from the front. Its only on the rear that you see the differences such as the model numbers. They both measure 44 x 40 x 21.5mm, which is slightly larger than the Z-Wave based Shelly Qubino Wave 1PM I reviewed recently. If your wall box is very small, this is something to keep in mind.

The Action button is a multi-purpose button, and apart from Zigbee pairing it even acts as an ON/OFF button for the relay. The ventilation holes are prominent on both the front and the back of the switches.

As this is a brand new product, it is not supported in my preferred Zigbee integration for Home Assitabt – Zigbee2MQTT (Z2MQTT). However, it is fully supported in Home Assistant’s official Zigbee software called Zigbee Home Automation or ZHA.

Installation & Wiring

The user manuals accompanying the Pico switches shows the wiring diagram for using the relay in a typical 1-way scenario.

With the help of a professional electrician, I installed the Pico Switch in a 2-way scenario in my laundry room. This is right next to the foyer where I have a Shelly Qubino Relay installed, so it will be fun to compare the responsiveness of these different relays later on.

The Pico Duo Switch was added to the existing switches for my living room LED lights – these are non-dimmable LEDs built into the ceiling. A Shelly 2.5 would be wasted here since the LEDs are dumb lights, so a relay without detached switch feature such as the Pico Duo is perfect here.

I recommend the Shelly 2.5 as the retrofit option if you have a smart bulb connected to a dumb switch that you want to retain. Using the detached switch feature of the Shelly 2.5 lets you keep the smart bulb powered on, and the physical switch becomes a virtual switch that you can then automate in Home Assistant.

In both instances, the external connected switches are double-pole toggle switches which is also the default setting in the Pico relays. You can always force the Pico relays to automatically detect the type of connected switch if you use something else (such as a momentary switch).

The terminal blocks of the Pico Switches are of the clamp type which makes wiring a doddle. There are also extra terminals for live and neutral connections. That makes it much easier to fit the relay into tight spaces without having to add extra Wago connectors.

Adding the Pico Switch and Pico Duo Switch to my Home Assistant Zigbee network

The best time to add the Pico relays to a Zigbee network is after wiring and before you put the relay into the wall. This is because there is a very helpful LED indicator on the relay that shows whether the relay is in pairing mode or not.

There are 4 ways to put the relay into pairing / inclusion mode:

1. Using the Touchlink feature which lasts only for 3 seconds after relay power-up
2. Pairing the relay within 180 sec of powering on the relay as it will be in pairing mode
3. Using the Action button (only possible before the relay is closed up behind the switch)
4. Using the external switch connected to the relay

I chose the action button method and these are the steps I followed for both the single and dual Pico relays:

1. Wire the Pico relay as per the wiring diagram. Wiring took more than 3 minutes after initial power on and during these 3 minutes the LED flashed quickly, after that the relay exited pairing mode by itself and the LED went into slow breathing mode.
2. Enable add/pairing/inclusion mode on your gateway (Zigbee Home Automation or ZHA).
3. Press the action button once, the relay is now in Zigbee pairing mode an the indicator LED will start flashing quickly.
4. Wait for a bit and when pairing is successful the LED indicator will enter regular light mode (constant blue light or off based on the state of the Pico Switch). If the LED is off, just click the action button to turn on the relay.

Here’s the success message I received in ZHA:

If pairing fails, Light Indicator will return to a slow breathe animation. There are a few things you should check before pairing again:

• Ensure you have a strong Zigbee mesh network – placing a wired Zigbee repeater device nearby will help.
• Do a factory reset by pressing and holding the action button for 17 seconds

Features

Looking at the device page in ZHA, we can see the various controls and sensors exposed by the Pico Switch and Pico Duo Switch:

The Pico relays support power consumption measurement and energy measurement. In ZHA, you also get some useful power-related sensors such as voltage, current, and AC frequency. These sensors enable the ‘Surge protection’ feature which will shut off the relay in case of a sudden mains power surge.

These relays also support overheat protection by using a built-in temperature sensor. You may have noticed that the device temperature value reported in ZHA in the screenshots above look wrong at 0.3 deg C, and they are! There is a bug in the ZHA device handler so it shows the temperature divided by 100. For now, the workaround is to create a virtual sensor with the value multiplied by 100.

When it comes to configuration options, the ZHA interface allows us to define the startup behaviour of the switch, say after a power failure. The default is previous state, and thats where I would leave it.

Performance

I like to look at the following areas when I judge a smart relay:

• Local operation,
• Responsiveness (both over the Zigbee network and the physical switch),
• Reliability,
• Power Measurement & Energy Monitoring,
• Signal strength & Repeater feature,
• Safety, and
• Cost

I used a NUC running the Home Assistant ZHA integration together with an Aeotec Zi-Stick placed in the garage. The Pico Switch is one concrete wall away from the co-ordinator and the Pico Duo is another concrete wall from the Pico. There are no other devices on this Zigbee mesh network.

Local operation

Zigbee allows for fully local operation without any need for Internet access or cloud reliance. So that’s an easy one, full points here just like a Z-Wave relay!

Responsiveness

This is probably one of the most important criteria to judge a smart relay on. Whether you are controlling the relay over Zigbee or via the connected switch, you want the relay to respond instantaneously.

I tested the Pico Switch relays extensively and found them to be very responsive with zero lag/delay when controlled over Zigbee.

Okay, how about using the connected physical switch? Let’s take a step back and define the context here. Any relay that supports connected switch actions other than a single ON/OFF command, such as double press, triple press, press and hold etc. will have a delay programmed into it so that it can decide whether a switch press is really a single press or will be followed by more quick press to turn into a double or triple press.

The Shelly Wi-Fi relays on the other hand have virtually zero lag/delay because by default it doesn’t wait to see if a press turns into an extended action.

Most smart relays however do support extended actions. For example, the Shelly Qubino Wave 1PM I reviewed recently is a Z-Wave smart relay which supports extended actions. But it has a rather annoying half a second delay when using the physical switch connected to it. Moreover, the delay is not adjustable.

So how do the Pico relays compare? Both the Pico and the Pico Duo relays do have a slight lag when controlling a connected load using the physical switch connected to the relay. Since this is not mentioned in the specifications, I asked Aeotec and they said the relays are programmed with a ‘maximum capture interval’ of 300 ms. This means the relay will wait for up to 300ms before turning on the connected load so that it can detect a double-tap action in the meantime. This is much better than the 0.5 sec delay I saw on the Shelly Qubino Wave 1PM but again it cannot be customised.

In practice I found that this slight delay in the Pico switches is tolerable and was not too confusing for little children or guests who were not used to a delay between turning on a switch and the light turning on.

Reliability

After using the Pico and Pico Duo Switches for over 1 month, reliability has been excellent. The smart relays have never gone offline, become unavailable, or failed to respond to commands from Home Assistant.

Power Measurement & Energy Monitoring

One of the biggest advantages of the Pico relays is the power and energy measurement feature. The power sensor starts reporting immediately after the relay is turned on. There’s hardly any delay and this is very useful for triggering other automations for the device you are monitoring.

Signal strength & Repeater feature

Opening the built-in visualisation feature of ZHA lets us check the signal strength and which devices are acting as routers.

As expected, the Pico Switch which is closer to the co-ordinator has connected directly to it, and the Pico Duo Switch which is further away has connected through the Pico which is acting as a router. Of course the Duo itself is also recognised as a router device. Sweet.

Signal strength with the Zi-Stick as the Zigbee co-ordinator looks solid across the board with the link quality hitting the maximum possible 255. Something I have never seen with my other Zigbee network running off a Sonoff Dongle-P.

Safety

The Pico & Pico Duo Switch relays meet all the safety requirements for such devices in the EU.

The relays have both overload protection as well as overheating protection.

Cost

I have found that while Aeotec products can sometimes be more expensive than competing products, they have high quality levels and that’s what you are paying for. Please check the latest prices using the Buy Now links at the end of this article.

The In-Wall Relay Competition

Sonoff has several Zigbee based relays, however I do have quality concerns when it comes to Sonoff devices that would go into my AC power wiring. The other popular option is Aqara which I have not tested personally but can be found a bit cheaper than the Aeotec Pico Switch.

Some Z-Wave alternatives are Aeotec’s own Nano Switch relay, the Shelly Qubino Wave 1PM, the Qubino Flush relays, and the Fibaro Z-Wave relay.

The VueVille Verdict

If you need a Zigbee relay that can switch up to 16A, act as a router, has power measurement and don’t mind a 0.3 second delay when using the physical switch, the Aeotec Pico and Pico Duo Switch relays re solid choices. Of course, there is zero delay when controlling the connected switch over Zigbee.

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