NEC Commercial Electrical Practice Test

Which of the following factors is NOT considered for determining the size of conductors between the controller and motor for a wye-start, delta-run motor?

1. Voltage rating of the motor

2. Motor full-load current

3. Environmental conditions

4. Length of the conductor run

The correct answer is: Voltage rating of the motor

The voltage rating of the motor is not a critical factor when determining the size of conductors between the controller and a wye-start, delta-run motor. Instead, the sizing of conductors typically focuses on the current that will flow through them, which is represented by the motor full-load current. This is crucial for ensuring that the conductors can handle the electrical load without overheating or causing damage. Environmental conditions are also important because factors like temperature, humidity, and exposure to corrosive elements can affect the performance and longevity of the conductor materials. Length of the conductor run is significant too, as longer runs can introduce voltage drops that may require adjustments in conductor sizing to maintain adequate performance. Focusing on these practical aspects ensures that the conductors provide efficient, safe, and reliable operation of the motor system throughout its life cycle. Therefore, the voltage rating itself does not directly influence the conductor size decision in the context of current-carrying capability, making it the factor that is not considered in this calculation.