So what's the definition of the "same power circuit" in all the instructions?

We have numerous power sockets in our home, but they're on 13 different groups (at least, that's what we call them in the Netherlands: parts of the house or individual devices with their own master switch). Also, our power supply is 3-phase (at least, that's what we call it in the Netherlands: our power is supplied by three mains lines of 230V each, and each mains supplies a subset of 4 or 5 groups).

So does the powerline adapter connection work only within the same group, within the same phase, or should it work across the entire house?

(I've bought this set for a connection within the same group, so I'm good either way for now, but I'm wondering whether this method could be used to extend the connection to the back room/home office, which is in the same phase, but on a different group.)

PS: The correct English terms for what I'm talking about are very welcome :-D