Motor Locked Rotor Amps (LRA) to Running Amps (FLA) Calculator
HVAC technician generator sizing, determining if a generator can start an AC compressor. Converts compressor and motor LRA startup spike ratings to running Full Load Amps (FLA/RLA) based on NEMA Code Letters (A to V).
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Calculations adhere to standard electrical engineering physics and National Electrical Code (NFPA 70) regulations.
Engineering Principles & Calculations
This calculator uses the exact mathematical relationships between Locked Rotor Amps (LRA), NEMA Code Letter (A through V, default G) to determine Estimated Full Load Amps (FLA), Soft Starter Recommended Sizing. In practical installations, factors such as ambient raceway temperature, harmonic distortion, duty cycle continuous operation, and conductor impedance must be accounted for by a certified electrician.
Converts compressor and motor LRA startup spike ratings to running Full Load Amps (FLA/RLA) based on NEMA Code Letters (A to V).
Typical Application & Industry Guidelines
HVAC technician generator sizing, determining if a generator can start an AC compressor.
Motor Locked Rotor Amps (LRA) to Running Amps (FLA) Calculator Benchmark Lookup Table
| NEMA Code Letter | kVA/HP with Locked Rotor | Typical LRA / FLA Multiplier |
|---|---|---|
| Code A | 0.00 - 3.14 kVA/HP | 3.0x - 3.5x |
| Code B | 3.15 - 3.54 kVA/HP | 3.5x - 4.0x |
| Code C | 3.55 - 3.99 kVA/HP | 4.0x - 4.5x |
| Code D | 4.00 - 4.49 kVA/HP | 4.5x - 5.0x |
| Code E | 4.50 - 4.99 kVA/HP | 5.0x - 5.5x |
| Code G (Most Common) | 5.60 - 6.29 kVA/HP | 5.8x - 6.5x (Avg 6.0x) |
| Code L | 9.00 - 9.99 kVA/HP | 9.0x - 10.0x |