Journeyman Electrician Practice Exam

What type of motor is served by 75ºC copper conductors rated for 80 amperes?

1. Single-phase motor

2. Capacitor motor

3. 3-phase motor

4. Universal motor

The correct answer is: 3-phase motor

The correct answer is 3-phase motor. The reasoning behind this is based on the characteristics and requirements of 3-phase motors in relation to conductor ratings. In electrical systems, a three-phase motor typically operates at a higher efficiency and power factor compared to single-phase motors. In the context of 75ºC copper conductors rated for 80 amperes, this conductor specification indicates a higher current-carrying capacity. This is a crucial factor since 3-phase motors often require more robust conductors to handle the increased load and power distribution effectively across three phases. Furthermore, using 75ºC-rated conductors helps ensure that the wiring can withstand elevated temperatures, which is vital in industrial applications where 3-phase motors are frequently employed. As these motors generally draw significant current, especially during startup, the conductor's rating must adequately support such demands while maintaining safety and performance standards. In summary, the context of the conductor rating aligns with the operational characteristics and electrical demands typical of 3-phase motors, confirming that this is the correct answer based on the provided information.