[DonRotolo]

There are 2 major considerations when sizing wire: Heat and Resistance Loss.

In a typical FRC robot, #12 will easily handle anything the robot can put on it, since there are 40A breakers on the PDB max. There is more than enough cooling air around the wires to prevent them from overheating. Plus, they are used for such short periods of time (~2 min).

But resistance is not your friend. A wire with 1.588 mOhms per ft, running at 40 Amps, will drop 0.064 volts per foot (and have to dissipate 2.5 watts per foot). From PDB to Jaguar/etc and then CIM might be 4 feet, so there's 8 feet of wire (4 black, 4 red), so you lose 1/2 volt there, all the time.

#10 wire would lose 2/3 of that, or about 0.3 volts.

Does 0.2 volts matter? Maybe. Depends. But that's how the numbers work.

1676 always uses #10 for CIMs, and the legal wire for every other circuit.