Tasmota Shelly EM

 I acquired a couple of these https://shellystore.co.uk/product/shelly-em-50a/  with extra clamps.

They are easy to setup & fairly well calibrated, I compared them against the supply meter for a few days.

But, They only provide Energy usage rather than Voltage, Current, Power factor etc, so I decided to flash them with Tasmota. https://tasmota.github.io/docs/

One of these makes it easy, a tasmotizer pcb, with a 3.3V supply onboard, runs from a USB C port on a PC, https://www.amazon.co.uk/dp/B0C15K9ZC4/ref=pe_27063361_487055811_TE_dp_2, designed & produced by RevK https://www.revk.uk/ & used with Tasmotizer software https://github.com/tasmota/tasmotizer

THESE SHOULD ONLY BE CONNECTED WHEN THE EM IS NOT CONNECTED TO MAINS POWER, DAMAGE & A SHOCK HAZARD EXISTS!

1st thing was discovering the smaller pin header has 7 pins, & the Shelly EM has only 6 sockets, easy enough to cut off the 7th, unused pin, the other end from the ground pin.

2nd, after a couple of tries, was discovering several flavours of Tasmota, the one for the EM is the 4M flash version.