Sorry, I misunderstood your earlier comment on the Tableís provenance.
Youíre right about extropolation from the particular (1 table) to the general (whole code), even when the table represents fundamental principles within the whole.
Notwithstanding, the ampacities given (in your representative table & ABYC tables) are higher than I (& I thought you) would recommend.
Since THHN is 75 deg insulation
, the free air rating of #12 would be 35A, thoí it still requires OCP at 20A.
➥ Lapp Online Catalog: National Electrical Code Allowable Conductor Ampacity
Originally Posted by S&S
They are standard tables (off the net) but they are in conformance with my copy of the Chicago Electrical
Festoon, festoon, feshtume (as I bespoke the word whilst typing).