HOLT Electricians Practice Exam

Which of these options is NOT a requirement for feeder conductors supplying multiple motors?

1. Size greater than 125% of highest rated motor FLC

2. Protection from short-circuits

3. Same ampacity for all conductors

4. Sum of currents of all connected motors

The correct answer is: Same ampacity for all conductors

The requirement that feeder conductors supplying multiple motors must have the same ampacity for all conductors is not applicable in this context. Each conductor's ampacity can be determined based on various factors such as the load it will carry, the ambient temperature, installation conditions, and local electrical codes. Additionally, feeder conductors can be sized differently if they carry different loads or are employed in separate branch circuits. In contrast, the other options highlight critical requirements for ensuring safety and operational efficiency when supplying power to multiple motors. For instance, sizing the feeder conductors to be greater than 125% of the highest rated motor full-load current (FLC) is essential to ensure that the conductors can handle the maximum expected load without overheating. Protection from short circuits is also crucial to safeguard the electrical system from potential damage or hazards like fire. Lastly, considering the sum of currents of all connected motors ensures that the feeding conductors are adequately rated to handle the anticipated total load without overloading.