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Motor FLA Lookup (NEC 430)

NEC table full-load amps with overload, breaker, fuse, and wire sizing per Article 430

Free motor full-load amperage lookup for electricians, panel designers, and maintenance planners who need NEC-compliant conductor and overcurrent protection sizing for motor circuits. Select motor horsepower, voltage, and phase (single or three-phase), and the calculator returns the NEC Table 430.248 (single-phase) or 430.250 (three-phase) full-load current. From that FLA, it calculates overload heater sizing per NEC 430.32 (115% or 125% of FLA based on service factor and temperature rise), short-circuit and ground-fault protection sizing per NEC 430.52 for inverse-time breakers, dual-element fuses, and instantaneous-trip breakers, and minimum conductor ampacity per NEC 430.22 (125% of FLA) with wire gauge from NEC Table 310.16 at 75°C. NEC 430.6(A)(1) requires using table FLA values, not nameplate amps, for conductor and overcurrent sizing. This distinction trips up apprentices and journeymen alike, and using nameplate current instead of table current is one of the most common code violations found during inspections of motor installations.

Pro Tip: For motors with a service factor of 1.15 or greater, or with a temperature rise not over 40°C, NEC 430.32(A)(1) allows sizing the overload at 125% of nameplate FLA. For all other motors, the overload must be sized at 115% of nameplate FLA. Note that overload sizing uses nameplate amps (the actual motor), while conductor and breaker sizing uses NEC table amps. This is one of the most commonly confused distinctions in Article 430.

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Motor FLA Lookup (NEC 430)
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How It Works

  1. Select Motor Parameters

    Choose the motor horsepower, voltage, and phase (single-phase or three-phase). For single-phase motors, the calculator uses NEC Table 430.248. For three-phase motors, it uses NEC Table 430.250. These tables cover standard NEMA motor voltages from 115V to 460V.

  2. Review Full-Load Amperage

    The calculator displays the NEC table FLA for the selected motor. This is the value required by NEC 430.6(A)(1) for sizing conductors and short-circuit protection. It is not the same as nameplate amps, which are used only for overload protection.

  3. Review Protection and Wire Sizing

    The output shows overload heater sizing (115% or 125% of FLA), maximum breaker and fuse sizes per NEC 430.52, and minimum conductor ampacity with the corresponding wire gauge from NEC Table 310.16 at 75°C terminal rating. Adjust for ambient temperature and conduit fill as needed.

Assumptions

  • Motor is a standard squirrel-cage induction type at standard NEMA voltages.
  • NEC table FLA values are from the current edition of NFPA 70 Tables 430.248 and 430.250.
  • Wire sizing is based on NEC Table 310.16 at 75°C in a raceway with no more than three current-carrying conductors.
  • Overload sizing assumes a service factor of 1.15 or greater (125% multiplier). Motors with SF less than 1.15 require 115%.

Limitations

  • Does not cover wound-rotor, synchronous, or DC motor sizing.
  • Does not apply ampacity correction for ambient temperatures above 30°C or conduit fill above three conductors.
  • Does not calculate feeder sizing for multiple motors on a common feeder (NEC 430.24).
  • Does not account for voltage drop over long conductor runs.

References

  • NEC (NFPA 70) Table 430.248 - Full-Load Currents, Single-Phase AC Motors
  • NEC (NFPA 70) Table 430.250 - Full-Load Currents, Three-Phase AC Motors
  • NEC (NFPA 70) Table 430.52 - Maximum Rating or Setting of Motor Branch-Circuit Short-Circuit and Ground-Fault Protective Devices
  • NEC (NFPA 70) Table 310.16 - Conductor Ampacities at 60°C, 75°C, and 90°C
  • NEC 430.6(A)(1) - Ampacity and Motor Rating Determination
  • NEC 430.22 - Single Motor Branch-Circuit Conductor Size
  • NEC 430.32 - Continuous-Duty Motors Overload Protection

Frequently Asked Questions

NEC 430.6(A)(1) mandates table values because nameplate ratings vary between manufacturers for the same horsepower and voltage. A motor might be nameplate-rated at 12.8A while the NEC table lists 14A for that HP and voltage. The NEC table values represent worst-case current for a given horsepower class. Using table values ensures that conductors and overcurrent devices are sized to handle any compliant motor installed on that circuit, not just the specific unit installed today. If the motor is replaced with a different brand that draws slightly more current, the circuit remains properly sized.
Overload protection (NEC 430.32) protects the motor from sustained overcurrent due to mechanical overload, such as a jammed conveyor or a worn bearing. It is sized close to the motor's FLA (115% or 125%) and trips on a thermal or electronic time delay. Short-circuit and ground-fault protection (NEC 430.52) protects the circuit conductors from high-magnitude faults. It is sized much higher (150% to 300% of FLA depending on device type) to allow the motor starting inrush current to pass without nuisance tripping. Both devices are required on every motor circuit, and they serve different purposes.
Yes, with conditions. NEC 430.52(C)(1) Exception No. 1 allows you to use the next standard size breaker if the calculated maximum (for example, 250% of FLA) does not correspond to a standard breaker rating. However, this applies only to the branch-circuit short-circuit and ground-fault protective device, not to the overload. For example, if 250% of a 14A FLA is 35A and the next standard breaker is 40A, you may use the 40A breaker. But the overload heater must still be sized at 115% or 125% of the actual nameplate current.
NEC 110.14(C) requires that conductor ampacity be based on the temperature rating of the lowest-rated connected terminal, not the conductor insulation. Most motor terminals, breakers, and disconnects are rated for 75°C. Even if you pull THHN wire (rated 90°C), you must use the 75°C ampacity column from Table 310.16 unless all terminals in the circuit are rated for 90°C. The exception is when applying ampacity adjustment factors for conduit fill or ambient temperature: you may use the 90°C column for derating and then verify the result does not exceed the 75°C column value.
Disclaimer: This tool provides NEC-based sizing values for standard motor circuits. Local codes, equipment manufacturer requirements, and specific installation conditions (ambient temperature, conduit fill, altitude) may require adjustments. Always verify with the applicable edition of the NEC and the Authority Having Jurisdiction (AHJ).

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