Article 210 in the National Electrical Code (NEC) covers branch circuits, with the exception of circuits that supply motor loads only. Article 430 covers these branch circuits, and Part II covers motor-circuit conductors.
Article 430 of the National Electrical Code (NEC) covers motors, motor branch-circuit and feeder conductors, motor branch-circuit and feeder protection, motor-overload protection, motor-control circuits, motor controllers, and motor-control centers.
Most of Article 240 in the National Electrical Code (NEC) provides general requirements for overcurrent protection and overcurrent protective devices not more than 1,000 volts (V), nominal. As a general rule, the overcurrent device rating shall not exceed the ampacity of a conductor.
There are many reasons for motor failures, such as overloading, bearing failures, rotor failures, worn shafts, and short circuits or ground faults within the motor windings, and contaminants that may enter the motor, causing short circuits or overloading.