Software vs. Hardware

Strictly speaking, IoTaWatt began as a software project with no specific hardware platform in mind. That objective was soon supplanted by an open hardware design based on the ESP8266. Typical IoTaWatt installations use a commercially manufactured unit that is certified to UL and CE safety standards and complies with FCC requirements.

The IoTaWatt firmware is factory installed and can be automatically and securely updated over WiFi. This section of the documentation deals with the physical installation of the commercial IoTaWatt unit with factory installed firmware.


IoTaWatt has 15 input channels. One is reserved for monitoring voltage, and the remaining 14 can be used to monitor power or voltage. The minimum requirements for operation are:

  • IoTaWatt

  • USB power supply

  • AC voltage reference transformer

  • Current Transformer (one or more)

Voltage and Frequency

IoTaWatt can work with all common line voltages at 50Hz/60Hz. Additionally, it can use multiple voltage references for polyphase measurement. The most common environments are 120/240V 60Hz and 230V 50Hz. The USB power supply and AC transformer must be appropriate for the power system.


Setup is simple:

  1. Connect the USB power supply to the 5V DC USB

  2. Connect the AC transformer to the 9V AC REF

  3. Plug the power supply and AC transformer into a wall socket

That’s it.

Next step: connecting to WiFi