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Originally Posted by Kevin Sevcik
As for the rest... many teams will attest that the standard wires to the drills aren't thick enough to handle current right now, and go to great lengths to replace them. I don't really think having wires that are too thick is THAT big of a problem unless you're really pick about easy routing or you're just that close on weight.
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Wire size and current carrying capability is based on temperature rise for a given size wire at a particular current. Al of our wiring is out in the open and not enclosed in conduit so that raises the amount of current it can handle. Also factored in are the lengths of a given wire as to how much series resistance will affect the voltage supplied to the load. Again our wiring is fairly short compared to real world applications. As to the blue wires for the drill motors, even if they were four time the series resistance of #10 they are only four inches long each and the insultaion is 200 degree C rated. #10 is .001 ohm per foot so even at 4 times the resistance, 8 inches of #16 wire is only .003 ohms. At 129 amps of stall current, that only drops a little more than 0.3 volts.
Whena a branch circuit breaker is chosen, it is sized to protect the wiring in that circuit from reaching a temperature at which the insulation will fail due to heat rise. Hence the #6 is protected by the 120 amp delayed action circuit breaker. The breaker will trip before current flowing through the #6 has a chance to heat up to the point of failure. Like wise for the 40, 30 and 20 amp circuit breakers. First mandates some apparantly larger wires for those circuits that teams have had trouble with in the past. You could wire your entire robot with #6, if you had enough weight under 130 lbs. but why.