[DonRotolo]

In regular house wiring, #10 is the minimum for 40 Amp circuits according to the NEC. However, in FIRST you can cheat that value a little bit, because we're dealing with generally accessible and open wiring, also generally used for 2 minutes or so.

The reason behind specifying wire gauges, such as for house wiring, is to prevent overheating, which can start a fire. Hot wires inside a wall is a disaster, but hot wires in a robot, in which the wiring is visible (if it smokes, people will see it), better cooled (a wire in free air can dissipate more heat than a wire inside a vinyl jacket (Romex) surrounded by fiber glass insulation), and used only intermittently (2 minutes at a time) is not as big of an issue. Not to mention the motors aren't drawing 40 A continuously.

There is nothing wrong with using larger wire - we do it at 1676, the added weight is small but the added power (reduced voltage drop) is compensation.

Don