In order to begin calculating the branch circuit or feeder size for a motor, the full load current (FLC) rating of the motor must be determined. Section 430.7(A) in the NEC^® provides a list of all required markings on a motor nameplate and the FLC is one of them.

Even though motors are marked with their FLC per 430.7, Section 430.6(A)(1) requires conductors to be sized using the full load current derived from the tables in Part 14 of Article 430 rather than the FLC from the motor nameplate for most installations:

430.6(A)(1) Table Values. Other than for motors built for low speeds (less than 1200 RPM) or high torques, and for multispeed motors, the values given in Table 430.247, Table 430.248, Table 430.249, and Table 430.250 shall be used to determine the following:

(1) Ampacity of conductors

(2) Current ratings of switches

(3) Current ratings of branch-circuit short-circuit and ground-fault protection

It is important to select the correct table. Table 430.248 provides FLC values for single-phase alternating-current motors while Table 430.250 provides FLC values for three-phase alternating-current motors. The text near the top of the table makes it clear that the table allows voltages ranging from 110 to 120, 220 to 240, 440 to 480, and 550 to 600 volts.

Refer to the image of the three-phase motor nameplate. The motor can be used in 3 different voltage configurations. The motor is not a low speed (less than 1200 RPM). It is not a high torque motor. It only has one RPM value (revolutions per minute) so it is not a multispeed motor. To size conductors and overcurrent protection for this motor, NEC^® Table 430.250 must first be used to determine the FLC rather than the FLC shown on the nameplate.

See the actual NEC^® text at NFPA.ORG for the complete code section. Once there, click on their link to free access to NFPA 70.