HOLT Electricians Practice Exam

What is the minimum ampacity for branch circuit conductors for a motor rated at 25 amperes?

1. 15 amperes

2. 20 amperes

3. 25 amperes

4. 30 amperes

The correct answer is: 20 amperes

The minimum ampacity for branch circuit conductors is determined by the expected load and the type of conductors being used. In this scenario, when dealing with a motor rated at 25 amperes, it is essential to take into account the National Electrical Code (NEC) guidelines. According to the NEC, conductors must be sized to carry the full load of the motor safely. However, conductors must also be sized to account for potential inrush currents that motors experience at startup, which often can be significantly higher than the motor's continuous rated load. Typically, for motors, a conductor ampacity that provides an additional buffer above the motor's rated load is specified. Thus, while 25 amperes might seem sufficient if taken at face value, the guideline would suggest selecting a conductor with a higher minimum ampacity to accommodate inrush current and ensure safety and compliance. Therefore, the appropriate choice would be to use conductors rated for 30 amperes, providing a safe buffer in line only with ensuring compliance with the NEC regulations when dealing with motor applications. This helps prevent overheating and potential tripping of the circuit. In summary, for a motor rated at 25 amperes, 30 amperes is the correct minimum ampacity for