$35 SONOFF POW ring smart power meter (POWCT) safely supports up to 100A

SONOFF POW Ring smart power meter is the first CT clamp-based WiFi power meter from ITEAD. It is designed for installation in an electric cabinet to measure whole-house power consumption with up to 100A current.

The power meter relies on an ESP32 microcontroller for control and wireless connectivity with a range of up to 130 meters thanks to an external high-gain antenna. It is supported by the usual eWelink mobile app that also enables integration with Google Home, Amazon Alexa, and IFTTT services, and ITEAD also mentions integration with the Home Assistant open-source framework.

SONOFF POW Ring smart power meter

SONOFF POW Ring (POWCT) specifications:

  • MCU – ESP32 WiFi and Bluetooth microcontroller
  • Connectivity – 2.4 GHz WiFi 4 (802.11b/g/n) with SMA antenna connector for an external antenna to be placed outside of the electrical cabinet
  • Current transformer (CT) interface type – RJ9
  • Current transformer detection range – 0 to 100A
  • Measurement category – CAT II 0-100A 300V Max
  • Built-in relay – 0 to 240AC and 0 to 30V DC up to 2A
  • Misc
    • Display to show power and energy consumption values
    • Button for power on/off (single press) or pairing mode (5-second press)
    • Power LED (Red), WiFi LED (Blue)
  • Input – 100-240V – 50/60Hz
  • Dimensions – 94 x 54 x 31 mm
  • Weight – 120 grams without accessories
  • Temperature Range – -40 to +50°C
  • Humidity – 5% to 95% RH, non-condensing
SONOFF POW Ring wiring
Wiring diagram (relay connection to contactor is optional if you only want to measure power consumption)

The SONOFF POWCT smart power meter ships with a 1-meter-long CT clamp, a WiFi antenna with a 30cm cable, a silicon seal ring, two screws, a mounting base, and a quick guide which you can also find along with a more detailed user manual on the SONOFF website.

Once the SONOFF POW Ring is connected to the eWelink app, you can check real-time, daily, monthly, and yearly power consumption in the Android/iOS mobile app, and also set timers, power consumption goals, configure voice control (Google Assistant and Amazon Alexa), Home Assistant, and automations through IFTTT.

eWelink Energy Consumption monitoring

ITEAD is selling the SONOFF Pow Ring smart power meter for just $34.90 on their online store, and as usual, you can also use the CNXSOFTSONOFF coupon to get a 10% discount on the device or any other item from the ITEAD shop. It’s not the first CT clamp smart power meter we’ve covered this year, but others are more expensive as they support more than one CT clamp to monitor multiple appliances. This includes the ESPHome-compatible “Smart Powermeter” with 6CT clamps and the Emporia Vue Gen 2 energy monitor with 16 CT clamps and support for both single and triple-phase power.

SONOFF POWCT accessories
SONOFF POWCT and accessories
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10 Replies to “$35 SONOFF POW ring smart power meter (POWCT) safely supports up to 100A”

    1. The user manual which is found in the sonoff site about this product (linked in the article) states a esp32 as MCU.

      Actually the second paragraph starts with the information about an esp32 so esphome or tamsota should be possible

    2. If it ESP32 then yes. But real question is – when we get support for HW inside like screen, power meter etc.

  1. The product design needs some work:

    1. Support multi-phase. In the US, most houses have 2 phase
    2. Elsewhere, 3 is common
    3. The display on the product is dumb. You only see it when the electric panel is open. How often is that?
    4. The product is way way too big. It looks like it is taking up 3 or more slots in the panel!
    5. Compare with https://www.shelly.com/en-us/products/shop/shelly-pro-3-em — 1 DIN slot for 3 phase measurement.
    1. If you have a “smart meter” in your home, no need for this device at all.

      Here in the Netherlands, about 90% of the homes have a smart meter. You can read your energy usage via the display, the physical P1-interface and (after your agreement) online.

      Works for 1 phase and 3 phase

  2. Can it work fully in 12VDC circuits (as in RVs)? I see its relay can switch DC, but what about measurements, etc?

  3. I entered this coupon code, it worked as expected -10%, but googling for same thing gives -20% coupon at two first results.

  4. It should be have RS485 for sharing consumption with other devices (like a solar inverter for zero export) and a second or third port for a clamp.

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