i've got 120' of 350/350/4/4 AL wire from transformer to a 400 amp service entrance meter/panel (Siemens MM0404L1400RLM). From there, the 200 amp feeder breaker is going to feed via 2 1/2" conduit to the future house.
That run is 235' to a temporary power panel to be used during construction ( Siemens PW0816B1200TC).
Is 4/0,4/0,2/0,#4 good? Or am I not allowed to down-size the neutral?