3-phase power system in Belgium

We have 3 Phase power system in Belgium.
I already own:
2 RaspberryPi 3
3 SCT013-00
Radio board is not needed.

what hardware you can recommend to read 3 phases?
What is the best solution to extend it later to 10 or 20 SCT013?
Delevery time for UK - Belgium

Quite a lot has been written here about 3-phase systems. The OEM products have all been designed for the UK single-phase system, so they are not designed with 3-phase applications in mind. There are three approaches that you can take.

  1. Use a single emonTx/Arduino with emonTx Shield and the 3-phase sketch to monitor the three currents at one point on the 3-phase system, plus one other current. The 3-phase sketch is an approximation and it has limitations, you can download and read the comments in the sketch for the details.
  2. Use one or more emonTx/Arduino with emonTx Shield on each phase, that is, you measure each phase totally separately. Each emonTx will be able to measure the current at 4 places but all 4 must be on its own phase. This is more accurate and easier to set up as the voltage of each phase is measured rather than guessed.
  3. Build your own analogue input circuitry and use a high-powered Arduino with enough analogue inputs to suit your needs, following the designs published here.

You will need to consider how the 10 or 20 points that you want to measure are shared over the three phases, and where you are able to install the CTs, to find the best solution.

In addition to one CT for each current that you want to measure, the 3-phase sketch will need one a.c. adapter, otherwise you need one a.c. adapter per phase, and (probably) a 5 V USB power supply common to all. There are so many options that I cannot give you an exact list without knowing exactly what you will do.

Email the shop - they will tell you the delivery time.

I had same question with emonTX Shield with no proper solution, then I build 3 -phase systems according to this:
I know that this link is somewhere in this forum earlier. And all credits to this author !!!

It is using Arduino Due and you have to build surrounding HW yourself. One Due can serve nicely 10 CT:s and accurate is amazing with 12-bit ADC.
I was so confident for this system that I build three separate systems, totally 24 measurement channels.
In original instructions RFM12B was used, but I do not use RF. I build them with Ethernet shield.
This system is using voltage measurement from one phase, but after calibration accurate is pretty good.
I spent quite a while for calibrating phase delay and phasecal, but when I finished values with one system, I just copy-paste all values to another systems. Only small CT line adjustments are then needed. (bearing in mind that AC plug has to be all the time exactly the same direction)

Regarding voltage measurement of each phases and approximation, I am not so worried about short time accuracy (< 1 min). It is in my case +/- 5%. More important is that longer term accuracy is good. I have calibrated my values using daily report from electric company and I can reach < 1.0% accuracy and is more than enough for me.