3 phase breaker feeding 2 separate panels,

[Kennedy1174]

We have a 1200 amp breaker feeding two separate panels in 2 different rooms one panel is 500 amps the other is 600 amp the 500 amp panel is feed with 350 cu
the 600 amp panel is feed with 500 cu IS THIS LEAGLE AND IF SO WHERE DO I FIND IT IN THE CODE
THANKS

 

[don_resqcapt19]

Those are tap conductors and you need to apply the rules in 240.21(B).

Neither of those are compliant as the overcurrent protection at the load end exceeds the ampacity of the tap conductors.