Not sure if the terms are official electrician terms
My 50 amp service is pulled up to a distribution/breaker box from the transfer switch. The distribution panel is split into two sections. The first section is a two phase 50Amp per phase section. The second section is a single phase section.
The service comes to dual 50Amp breakers from the transfer switch. The two 50A breakers apply power to the two phase distribution panel. This two phase panel has (for me) a 30Amp breaker that goes to my Magnum 2812 inverter. The inverter has an internal transfer switch which selects the 30 amps coming from the breaker or the 120VAC output of the inverter and puts that on a 30 amp service to the second distribution panel via a 30 amp baker. The inverter driven panel is a single phase bus with breaker for all the circuits that the inverter supports.
If I were to upgrade the inverter circuit to 50 Amps I would put in a 50Amp breaker instead of th 30amp to the inverter. Pull the appropriate wire for 50Amps to the inverter. Pull appropriate wire from the inverter to the second distribution panel, and put a 50Amp breaker on the second inverter panel. This assumes the inverter can handle 50 Amps on its internal transfer switch.
2013 Winnebago Journey 36M DP. Full time since 2015.
1987 FJ60 Flat Towed, Blue Ox Tow Bar (not recommend), SMI Air Force One, 2000 Watts Solar, 600AH LifeBlue LiFePO4 batteries (excellent).