[Al Skierkiewicz]

A rule of thumb I have promoted for many years is the wire foot. Simply stated a foot of #10 wire will drop 0.1 volts at 100 amps. Since #6 is twice the size of #10, the same current would drop the same voltage in two feet of #6. This is a linear relationship so you can increase the current decrease the the wire size and still come up with a rough idea of the voltage drop. Remember you must consider both sides of the wire, red and black. Since the #6 wiring carries all of the robot current, it is possible with a four CIM drive to easily pass 400 amps through this wiring. For your change you added 5 feet of wiring so the expected drop would be 0.4 volts for every 2 feet, or about 1 volt for a 400 amp load current. The following lengths are equivalent for WF calculations.
2' #6
1' #10
8" #12
6" #14