HomeHome AutomationAmped to 25 - Sonoff POWR3

Amped to 25 – Sonoff POWR3


It wouldn’t be the first time I come across a comment or email about device X having a bigger current limit than Sonoff devices. Averaging about 10A per channel, I never got even close to reaching the limit on the ITEAD’s devices I own. There are always edge cases out there, but it’s safe to say that for us, average mortals, that limit was never an issue. It looks like folks at ITEAD had been reading the same comments as Sonoff POWR3 (ITEAD Store) comes with a massive 25A current limit. I’m pretty sure that won’t stop some people from complaining.

Sonoff POWR3 in detail

Sonoff POWR3 and Sonoff POWR2
Sonoff POWR3 and Sonoff POWR2 – family picture!

If you thought Sonoff 4CH (review) were big, think again. Sonoff POWR3 is absolutely massive. It’s bigger than Sonoff 4CHPROR3 and comes with a whopping 5500W limit. A massive improvement over the Sonoff POWR2 (review) which was capable of 15A in a single channel. There is a reason why the latest relay is this big, but first, let’s go over the specification.

Despite the humongous size, Sonoff POWR3 comes with a single channel. It’s a disappointment for the unit this big, but it is what it is. Thankfully, it shares the correct number of terminals, so you don’t have to use external connectors to wire it up.

Apart from relay control, Sonoff POWR3 is capable of measuring power consumption as well. On the front, you will find the relay control button and a restart button. Flipping the case to the other side reveals a DIN-rail mount and a retractable hook for a screw mount.


Input100-240V ~ 50/60Hz 25A Max
Output100-240V ~ 50/60Hz 25A Max
Max Load25A/5500W
WiFiIEEE 802.11 b/g/n 2.4GHz
Working temps-10℃~40℃

There was no direct information about inductive load (the specification refers to resistive) but in the CE paperwork, I come across 0.6 pf (power factor applicable to inductive loads, 1.0 for resistive) – hope this clears things up a little.

Sonoff POWR3 is available on the ITEAD store for $30.79. On one hand, it feels expensive for a single channel relay, but if your needs go beyond the Sonoff POWR2 15A limit (at half the price), then it might be one of the cheaper options out there with a similar power rating.

Sonoff POWR3 - schematic
Sonoff POWR3 – schematic

Power Measuring

POWR series comes with the ability to measure power use. It’s the first time I also came across the setting responsible for the cost calculation (Update: It wasn’t the first time, my memory needs upgrading, the feature was available on Sonoff POWR2). Sonoff POWR3 lets you set the price per kWh and display the associated cost of running the unit. Just bear in mind, that the eWeLink app has no support for multiple tariffs at this time.

Power consumption data can be downloaded or displayed as charts in the app. In addition to that, you can also monitor the power consumption in custom ranges. Simply set the start time and continue monitoring until you stop the range. You will be able to export the data once the custom range is finished.

Other options

It’s a fully-featured device that comes with extra settings like OPS protection (voltage/current/power), default power-up state and inching.

Sonoff POWR3 supports LAN only mode, but despite the big DIY label on the box, Sonoff DIY mode isn’t mentioned anywhere. Has ITEAD abandoned this forever? The DIY mode was a great option for anyone interested in 3rd party integrations without Tasmotising devices. Alternatively, for anyone interested in going down this path, take a look at eWeLink API to connect your devices via Cloud API with NodeRED or Home Assistant.

Speaking of 3-rd party integrations, Alexa and Google Assistant are supported thanks to eWeLink skills. If you are looking for these integrations – that is. Timers and scene support is already integrated into Sonoff devices thanks to the eWeLink app, so I don’t think I have to mention this anymore.

Inside Sonoff POWR3

Inside the Sonoff POWR3
Inside the Sonoff POWR3 (easy job thanks to ES121 Screwdriver)

I wasn’t sure what would I find inside. Getting there was easy, thanks to 4 screws and my MiniWare ES121 Electronic Screwdriver (review). Turns out I found two things: ESP8266-EX running at the hear of the device and the answer to the question of why Sonoff POWR3 is so big. Unlike other Sonoff devices with power measuring capabilities, this one has a current clamp inside. There is literally a thick wire threaded through the current clamp and connected to the output terminal.

Speaking of terminals, they are well made and should sustain high current use. Connecting wires are also properly terminated and covered with silicone insulation to increase fire resistance.

Sonoff POWR3 is split into 2 PCB boards. One handles the relay (rated 30A) and hosts the ESP8266 chipset, the other one acts as a small transformer splitting mains input into 5V for relay control and 3.3V for ESP8266. I’m not an electronics engineer but both circuits feel reasonably separated on the PCB and overall impressions are positive. Consumers can rest assured that this unit comes with CE, ROSH and FCC certificates available online.

Underneath the Sonoff POWR3 sticker hides “Custom Sonoff POWR2 by OYO” – looks like I was shipped one of the early versions. Anyhow, thank you OYO for the upgrade!


Since Sonoff POWR3 is ESP8266 based, the first question on everyone’s lips will be: can we Tasmotize it? PCB reveals a large number of GPIO pins already broken down into connectors and PCB test pads.

Here is the list of the available GPIO:

4-PIN connector with headers:

  • 3.3V
  • GND
  • ETX
  • ERX

Pinholes on PCB:



  • GPIO00 – Power Button
  • GND/ADC pair
  • GPIO15 /GPIO16 pair

I’m yet to find the relay pin, but I will poke around more when flashing Tasmota on it. I will cover this in a separate article so if you want to follow along expect that article to appear soon.

Final thoughts

Haters gonna hate the size, anyone else will appreciate the 25A limit and the power measuring features. I would love to see a 2 channel version of this product and the support for dual tariff cost as anyone running the built-in cost estimate will find some inaccuracies if running more than one tariff. 25A is a lot of juice. It’s a perfect device to control power-hungry heaters, AC units, and equipment usually present in more industrial settings. How would you use Sonoff POWR3 (ITEAD Store)? Oh, if you want to see it flashed, the guide is ready now. Let me know in this Reddit thread.

🆓📈 – See the transparency note for details.


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