Don Klipstein wrote:

Since resistance increases with temperature, actual ampacity does not
increase much with an increase in temperature rating. And ampacity
according to the code does not increase at all.

I'm going to have to disagree with that.

For simplicity, look at the "single conductor in free air" tables. (The
other tables show it too, just the absolute values are lower.)

With 60-90C rated insulation, a #14 wire is rated for 20A. With
110-125C rated insulation, that same size wire is rated for 40A. If you
go up to 200C insulation, you can put 45A through it.

Chris