Looking at a building operating at 120/240V 3P 4W. Incoming is 3 sets of 600MCM THW AL. all 3 sets connect to the input of metering CT's. On the output of the CT's are 3 sets of 500MCM THW CU but each set goes to an individual 3-phase panel with 400A-3P main. Basically, 3 disconnects. Is this viewed as 1 set of conductors per panel after the CT and parallel before the CT? I am trying to determine ampacity for additional load. Looking at 400.4(B), it looks like the 500 are correct from the output of the CT to each panel (380A conductor and 400A CB is next), but how would it work on the incoming 600MCM AL?