This is a project to report the whole house electricity use via a web page. See FridgeMonitor.

Bought:

• SCT-013-000 Non-invasive AC Current Sensor Split Core Transformer 100A ​Amazon
• NodeMCU ESP8266 module
• Cheezy Arduino rip-off ("Elegoo")

Installed the power monitor library from openenergymonitor.org. Hooked up to sensor with 33 ohm load resistor and wrote a bit of code. Tested with 100W incandescent bulb and seems to work OK.

Rearranged wiring a bit in the electric panel so two of these sensors can fit on the main feed wires.

Turns out the NodeMCU only has one analog input (sigh). Best bet now is to use a prototype shield board to mount the NodeMCU and use it as a WiFi? interface for the Arduino. This has the advantage that the libraries etc should just work, and can be tested with the serial monitor easily. Also would make a nice platform for future things which want to measure multiple analog quantities.