Noozer did his best to answer your question.
Personally I was not able to understand it clearly enough to answer
So unless you are willing to restate your original question more
clearly I sincerely doubt you will get a better answer.
:"I would like to confirm that, according to the NEC, there is no
why you cannot use 12/3 connected to 15 and 20 amp breakers (one on
pole A the other on pole B) and then (say 30 feet away) branch into two
circuits (a 15 amp circuit on 14/2 and a 20 amp circuit on 12/2).
So does this mean you're:
running 12/3 from a 15 amp breaker
& also running 12/3 from a different 20 amp breaker
or have you created a shared neutral situation?
and then ~30ft away "branch" (branch what or which; each original
into two two circuits (a 15 amp circuit on 14/2 and a 20 amp circuit on
is each original circuit be branched or just one of them?
do you intend to install the proper sized breakers to protect the 14/2?
bottom is 12/2 ok on 20 amp breaker, 14/2 is only ok when protected by
a 15 amp breaker
fyi when you're asking for free advice try not to piss of the guys with
why the mixed breaker & wire size?
Just run it all in 12/3 & simplify your life.