Ok, after another soda I have found a large error in my assumptions.
Since this is SE cable, I am assuming that the conductor connects to a CT then a circuit breaker. Both these devices have a 75ºC terminal temperature rating. With that the Al and Cu conductors carry a max of 65A(I) for #4 & #6 respectively.
I am also assuming V(E) at 208, ambient for the ground at or less than 36" depth at 60ºF and above ground at 105ºF, 3 phase power. Soil thermal conditivity(RHO) is also assumed at 90.
The conductor impedance(Z) values are .02571 for Al and .05566 for Cu at 45' and 82' respectivly.
Ztotal = 0.08137 ohms
Vd = I * Z = 65 * 0.08137 = 5.28905
%Vd = Vd / V(E) * 100 = 5.28905 / 208 * 100 = 2.54% Vd with the above assumptions. If V(E) = 480 or the SE cable is connected differently or any of my other assumptions are different, then these values are wrong.
And I agree with George Little, there are too many assumptions.
Opps, I guess I was writting this when Roger posted, I also agree with Roger.
[This message has been edited by DiverDan (edited 09-24-2005).]
