Here's another idea.. drawing on your electrician experience.

Make a program that reads a text file, which sort of mimics a panel schedule, but on each line instead of a load current, it has a voltage/resistance. With the goal being to find and add up the currents and spec a cable that can carry it all.

1) Find out how to open a file in python

2) Learn how to read it line by line

3) Process each line and find out how to pull the values and calculate the current, add to a list

4) At the end, add up all the values and figure out how to specify the right gauge wire

5) Print output