First, let me preface this by saying this is entirely theoretical. I don't plan to install anything myself, and I'll contract a licensed electrician to do any of this work, so please don't feel the need to post warnings, disclaimers, or otherwise explain the dangers of mains electricity.
Given that, I have learned that my utility company provides 240V to the meter at my house. There is a breaker box immediately downstream of the meter, and it services 100A at 120V (so it becomes split-phase at some point). After a bit of conduit, I have my current breaker panel, with its circuits going off into the house.
Assuming that I am correct in that there is a center-tapped transformer stepping the meter voltage down to 120V from 240V and, therefore, provides two phases (we'll call them "Phase 1" and "Phase 2"), this means I have 240V, Phase 1 120V, and Phase 2 120V available to me, even though I am only using Phase 1 120V.
I want to have three total breaker panels, one for each Phase 1 and 2, and 240V, but there is also that 100A breaker immediately following the meter to deal with.
My question is, what is the best way (schematically) to install 300A (I can get up to 320 from the meter without an upgrade) of breaker to protect all three circuits?
My current thought is that I would need a 300A breaker on the Phase 1 hot wire and a 300A on the Phase 2 hot wire. Is this correct, or is there a simpler/better way to arrange this?