I am looking for advice with regards to how to determine what is the best conductor layout on an underground trench; using direct burial conductors for multiple (10) ~ 500Vdc circuits.

I did read the Section Characteristic impedance, on Chapter 14 of the book; and found an interesting explanation of how capacitance and inductances depends on cable separation; but this theoretical exercise was done on an infinite tranmission line.

My case is real and has a limited lenght of 198 mts for the longest run, and about 20 mts for the shortest. How could I find the optimum conductor arrengment in order to minimize the losses (highest transmission efficiency possible)?

Please advice

Thanks

Miguel