I have done more thinnking about this in the past few days. I have rewritten everything in terms of the heat dissipated by conduit and and generated by the conductors.
It is certainly easier to read and the math is more correct.
I placed a paper in Word format on my recreation site. Sorry it is not HTML.
www.robertscpa.com/kayaks/conduit_sizing.doc I found some stuff at
www.electrician.com/articles/ampacity.htm
