I have a Sq. D meter stack with 3 200 amp breaker slots but the bus is only 4rated for 400 amp. I installed a 400 amp service loop to the main lugs of the 3 gang stack. I am being told that this is not allowed because the 3 breakers can add up to 600. Why would Sq. D make a 400 amp bus with (3) 200 amp slots if it wasn't acceptable.