lol…WHAT…all you guys in FLORIDA have the potential for indoor pools…now that sounds EXCLUSIVE…lol…
lol…as you stated greg…how many people ACTUALLY derate the NM-B running through their attic to the outside AC unit…
Regardless…you all made my BASIC example…no longer BASIC…lol
how do I attach a pic to quick reply???
I dont think you can Brian…you have to go into advanced I believe
I can always get people to whip out the calculator when I start this derating thing. It is never pretty.
I ran 6ga through my attic to pick up the air handler and condenser (Trane specs this as an option in the big manual). The A/H is the “big” load because of the toaster wire heater but the attic is cold then. In the summer it is overkill for the condenser but the derating works.
If ya look at the tables I posted above they list “Minimum Circuit Ampacity” for selecting the wires, which equals 125% of the Comp RLA plus the Fan Motor FLA. The Min Fuse/Breaker seems to be 175% of the Comp RLA rounded off, and the Max Fuse/Breaker seems to be 225% of the Comp RLA rounded down.
You probably shouldn’t multiply the "“Minimum Circuit Ampacity” by the 175% or 225% factors, as that already has a 125% factor included for continuous load. Also NEC 440.22 requires using the “rated-load current” (or RLA) for figuring the max fuse/breaker sizes (they dont list a “branch circuit selection current”). Went through this with a manufacturer on a past project a while back where there was a question.
It can get pretty confusing for HI’s (particularly when ya start adding in things like voltage drop and temperature derating), where it’s better to just check the nameplate with what is installed and look for visible signs of defects.
Most HI’s are aware that breakers for AC condensers can be larger that usual, but I thought it was worth pointing out here that the usual HI rule of thumb for copper wire of #14=15A, #12=20A, and #10=30A doesn’t apply to AC equipment … but in some cases pushing things to the limit can result in issues if everything isn’t considered. And “when in doubt, bail out” … 
JMO & 2-nickels … 
P.S. Ran across a calc example for an AC condenser in Mike Holt’s book “Understanding the National Electric Code” under Article 240.4.G with a nameplate listed Comp RLA of 18.0A and Min Circuit Ampacity of 23A
Min Circuit Ampacity is 23A (18A RLA x 1.25 = 22.5A, rounded up)
Wire Size is #12 THHN (rated 25A at 60C)
Max Fuse Size is 40A (18A RLA x 2.25 = 40.5A, rounded down)