Is it really required to actually read currents to achieve the power measurement? do meters in individual buildings not have interval-flashing LED's for power consumption in the US (I'm assuming the target market is the US)?
A flashing LED is neat because you can then use a very simple-to-install adhesive photodiode to count the flashes and radio the results back to some reader (e.g. 1000 impulses per kWh). Doesn't require an electrician because you never actually tamper with the meter, unless you want to leech a tiny bit of power to your transmitter.
The normal connection here is a big outdoor box for the incoming line, with 3 main fuses, one for each phase. Typically 3x25A @ 230V for a detached home (Max ~17kW). This is where you want to read the power consumption. Inside the house there is a box with 3 DIN rails (1 per phase) with switch type fuses. With 3 phases it's a lot harder to read the power consumption there than it is at the outside main fuse box (which is unfortunate, because it's a lot more convenient to mount a meter indoors and near a wall socket, than outside inside a thick steel box without easily accessible power for your power meter+radio).