so this task force is basing the changes on "rounding" and to "harmonize" the two. how about they get real data like i describe and revamp the whole table based on data. it boils down to how hot the insulation of wire gets when installed per the allowable installations and wire types. since NEC is way over conservative, using a base # like 1.02W/ft@100ft (<-- notice it is not wire specific, the table i gave a few posts back was for copper) would make the ampacity table more accurate, and the code wouldnt need all these wacky exceptions. it would also make it very simple to calculate if the next wire up is needed. i am not even sure if the derating would be needed for 4+ CCC's in the raceway if there is a max fill # to begin with. you can adjust max fill # perhaps down just a tad, this should be enough to accommodate x # of wires in raceway up to max fill @ 1.02W/ft@100ft, you would get max watts when all wires were #14 because under my insanely proposed std each wire would generate same max heat, thus putting bigger wires into the raceway would mean less wires and thus less generated heat, etc.
but sure, NEC is what it is, some of it makes no sense to me as to how/why the verbiage is the way it is. i myself like to see those lab tests, or FD reports showing real data, etc.
