Journeyman Electrician Exam (NEC)Equipment and DevicesMedium
A journeyman electrician is installing a new 3-phase, 480-volt, 30-horsepower squirrel-cage induction motor. What is the full-load current (FLA) of this motor according to NEC Table 430.250?
- A48 amperes
- B27 amperes
- C40 amperes
- D34 amperes
Show answer & explanationAnswer & explanation
Correct answer: D. 34 amperes
According to NEC Table 430.250, for a 3-phase, 480-volt squirrel-cage induction motor, a 30-horsepower motor has a full-load current (FLA) of 34 amperes.
Why the other options are wrong
- A. This is the FLA for a 50-horsepower, 480-volt, 3-phase motor.
- B. This is the FLA for a 25-horsepower, 480-volt, 3-phase motor.
- C. This is the FLA for a 40-horsepower, 480-volt, 3-phase motor.
Motor Full-Load Current (FLA) from NEC Tables
Standardized full-load current values for various types, horsepowers, and voltages of motors, as provided in NEC Tables (e.g., 430.248, 430.250), used for sizing conductors and overcurrent protection.
- Used when the motor nameplate FLA is not available or for general calculations.
- Tables differentiate between single-phase and three-phase motors.
- Different tables for different voltages (e.g., 115V, 200V, 208V, 230V, 460V, 575V).
Memory trick: Horsepower, voltage, and phase, NEC table guides your amperes!