Cheap power meter, 12 bucks

[berniebenz]

Originally Posted by Xringer

One side is going to be just a pass-thru, and a common for the internal DC PS & an AC voltage measurement point.
The other side (red?) will be tapped for voltage measurement, and the internal DC PS.
That side will likely have a non-contact current sensor. (like a clamp sensor).
But it could have a plain old resistor sensor, like a Killavolt.
The only problem I see is your meter board would not have a ground or neutral. (floating).
And part of the board would be electrically 'hot', relative to ground.
If you put the meter in a metal box, you could ground it to neutral..

The black wires in and out are thru a current sensing resistor. The red wires are just a pass thru so only one needed to power the meter and could be tied to the other side of 220AC or to neutral.