derating question

[wireday]

When derating for conduit fill at 4-6 ccc at 80%,does it matter if 2 conductors are running different amperage than the other 4 conductors. I have one circuit 30 amp and two others at 20. The 30s are on #10 and the 20s are on #12 after proper derating,

 

[infinity]

No it doesn't matter all you are doing to adjusting the actual ampacity of the conductors. If you have 90° C conductors like THHN then the #10's are good for 32 amps after derating and the #12's are good for 24 amps. If after the adjustment they are too small you would need larger conductors.