[Al Skierkiewicz]

Andy,
Yes you can, the wire size minimum is listed by the breaker feeding that branch. i.e. a 40 amp breaker can be used with #12 wire but I recommend #10 for CIM motors. The wire size is chosen for safety and voltage drop from the NEC handbook for open frame DC wiring. If #14 wire was used with the 40 amp breaker, it is possible to heat the wire to the point at which the insulation fails. #12 wire on the other hand may get warm but not to the point at which a failure would occur. A dead short of course, would be protected by the breaker. At 100 amps, the #12 drops ~0.2 volts per foot. In a typical robot wiring job I would expect to lose almost a volt at the motor input during starting and heavy loading with a fully charged battery.