[JoelP]

With the electronics we had last year, we would connect the cim to 40amp breakers, so if the cim drew more than 40 amps you would trip the breaker(s). Usually this happens when you gear your drivetrain too high, so it does not have enough torque. This would result in the robot not being able to accelerate fast enough and therefore the motors would be pulling more than 40amps for long enough to trip the breaker(s). Also, if the wheels you use have high enough traction, but your drivetrain doesnt have enough torque to make these wheels spin, the cims will stall and eventually trip breakers.
And, I've never seen this happen but I think it's possible, if you have 4 cims in your drivetrain and they pull over 30 amps each, you could trip the main 120amp breaker switch before you trip any of the 40amp breakers, which would leave your robot inoperable for the entire match.