Motor Starter Sizing Calculator

Motor Starter Sizing

Determine the correct motor starter, overload relay, and wire size for electric motors based on horsepower, voltage, and starting method per NEC requirements.

Motor Horsepower

Voltage

Starting Method

Service Factor

Formula

FLA (3-phase) = (HP x 746) / (Voltage x 1.732 x Efficiency x PF); Overload Setting = FLA x Service Factor x 1.15; Breaker Size = FLA x Start Type Multiplier; DOL = 2.5x, Soft Start = 1.75x, VFD = 1.5x

Frequently Asked Questions

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