Hey good point in what you pointed out!
each bundle is smaller in size as the piece of plastic in the center. I will get you a number when I go home next, in about 2 wks.
yes the center plastic core is 0.175 in diameter, what I did was simple subtract the core out of the major diameter to yield me a new diameter.
The total diameter jacket included is 0.7 (so almost 3/4 of an inch) the conductor diameter with the core is 0.45 (so almost 1/2 of an inch thick) which means the jacket 0.25 (so a 1/4 of an inch) think.
now I took the conductor diameter and subtracted the core diameter from it to get my new diameter of .275 (which is larger then a 1/4 of an inch) so this left me to believe that the core was about 1/4 % of the conductor diameter.
now I said the conductor is 40% of the total diameter, the jacket is 38%, which leave the core to be 22% of the overall total diameter. Keeping in mind that the 6 copper strands are smaller in diameter (not sure by how much but enough). Now if the copper and core was the same size then this would make your math work out to about ~14% as you stated above but since the copper is smaller than the core this make the percentage of the core increase. If this make sense. Well it did to me at the time back in the day lol.
let me know what you think also I when I go home next I will get you a picture of the core being measure, along with one of the ropes of copper and maybe I did this wrong from the get go but we will figure it out! in about two weeks time.
as for part 3 ya load testing a piece of 1/0 vs another piece of 1/0 in a LAB would be expensive. Now if I had a carbon load and a steady power supply then I could do it but those are expensive and I just got out of school.
I might actually do a load test on some of the wires in my own car one day when I buy a clamp meter, as kind an amateur thing but that is about all. I assume I will find out that each wire will be able to handle the load about as good as the next but we will see lol!