sizing conductors

[slc410]

when sizing a conductor within a raceway does the adjusted ampacity sizing of the conducor need to continue down junctioned raceways utilizing less conductors. For instance if I have a #10 THHN conductor that was increased in size for a 20A ocpd then that raceway junctions to a box with other branch conduits could I then decrease the wire size to a #12 THHN?

Code Article would be great!

 

[infinity]

You can treat every section of raceway which has different amounts of CCC's as separate raceways. For example the first section of raceway between a panel and a junction box utilizes over sized conductors due to derating. If those conductors now separate into several different raceways those secondary raceways will only require derating based on what's in them. So if you continue with a lesser number of CCC's, derating might no longer be required and smaller conductors may be used. Best I can come up with is 310.15(B)(2).

Welcome to the forum.

 

[slc410]

Thanks Rob!