splicing to different size wires with proper amperage rating

[JH13]

i am doing calculations for wire size needed after derating for amount of conductors in the conduit. my question is: can i down size my wire once i hit the gutter and all circuits are split up into different runs? or do i need to continue the same gauge wire to all of the equipment even though no derating is needed when they exit the gutter?

 

[ActionDave]

As long as you don't exceed 30 ccc in any cross section of the gutter you can change wire sizes.

 

[infinity]

As Dave stated in the wireway once you exceed 30 CCC's you'll need to derate. If you don't have more than 30 CCC's at any cross section then you can use smaller conductors without any derating being applied.