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IoTaWatt - WiFi Connected 14 Channel Electricity Monitor

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  • IoTaWatt wall mount Installed
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  • *mobile device not included
£151.08 (inc VAT) £125.90 (exc VAT)
150.00 Grams
Calculated at checkout

IoTaWattTM is an open-hardware 14 channel WiFi connected AC electric power monitor. Developed and supported by Bob Lemaire (@overeasy).

The IoTaWatt based on the ESP8266 IoT platform using MCP3208 12 bit ADCs to sample AC voltage and current at high sample rates. Data is saved locally to the on-board SD card and (optionally) posted online to Emoncms.org or another Emoncms server e.g. emonPi. On-board data storage ensures no data-loss in the event of network failure. If network is lost data saved locally will be bulk-uploaded to Emoncms when connectivity is restored.

The IotaWatt is configured via a web-interface, see online demo: iotawatt.com


Read IoTaWatt Customer Review



  • 14 x single-phase or three-phase* AC current sense (CT) channels
  • 1 x AC VRMS Channel
  • Compatible with multiple types of CT sensors and AC-AC voltage sensor adaptor
  • Local SD card logging 
  • WiFi connected to post to Emoncms / InfluxDB
  • Sample rate: 35-40 channels per second
  • Voltage (VRMS), Power (W) and Energy (kWh) logged to local SD card every 5s
  • On-board Real-time-clock (RTC) with battery backup
  • Web-config interface config
  • Secure automatic OTA firmware updates  
  • 5V Micro USB power supply
  • Wall mountable 

  • Open-source / hardware
  • CE certified
  • RoHs compliant 


* See IoTaWatt setup wiki for more info on monitoring three-phase

The IotaWatt has been designed and manufactured by Bob Lemaire (@overeasy) in collaboration with OpenEnergyMonitor. 



  • IotaWatt tm fully assembled & tested
  • 8 GB on-board SD card 
  • Wall-mount bracket 
  • (optional) AC-AC voltage sensor adaptor (highly recommended for accurate Real Power measurements)  
  • (optional) 5V DC Micro USB power adaptor (essential: battery operation not supported) 


Does not include 

Required for operation, purchase separately:

Clip-on Current Sensor (CT's)

Compatible with:

 Note: It's possible to mix and match CT's on the IoTaWatt e.g. have a number of large CT's and smaller CT's all connected to a single unit 





Getting Started



To obtain IotaWatt support or report a bug please either: 

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