For a project wtih a fablab, we have using a Li-Polymer Charge Management Controllers MCP73831
You can have free "sample" for prototype if you ask directly to the factory, perhaps it could be faster.
For precision, I've just one phase at home, but I want few Amps meter for different "sectors" of the house.
My question was: Is it a good idea to use the transformer (I've a AC 220V to AC 12v 3VA) for both using: power supply of the sensor (with rectifier bridge and capacity and regulator) and for voltage meter (with divider bridge as you do in your sensor).
Or it's a bad idear: Is it possible, in this configuration, to generate a voltage variation when arduino send informations?
I have a question about your sensor
I want to do a similar sensor, with 3 or more Amp meter but just one voltage.
Is it possible ( or a bad idear) to use transformer for measuring voltage and use as power suply (with regulation 5v and 3,3v) for sensor?