Motor Circuit Calculator
Branch circuit protection, conductor, and starter sizing from motor HP per NEC Article 430.
Inputs
Results
Motor FLA (amps)
14
Max OCPD size (amps)35
Min conductor ampacity (A)17.5
Selected conductor ampacity (A)20
Overload relay trip (A)16.1
Conductor index0
StarterNEMA 1 (up to 18A)
Ground Wire10 AWG
How to Use This Calculator
- Enter the motor nameplate horsepower rating.
- Select single-phase (1) or three-phase (3) and the supply voltage (230 V single-phase or 460 V three-phase are common).
- Choose the protection type: inverse-time breaker (1) at 250% FLA or dual-element fuse (2) at 175% FLA per NEC 430.52.
- Read the full-load amperage (FLA) from NEC Table 430.248/250, the maximum overcurrent device size, and the minimum conductor ampacity at 125% of FLA.
- Use the overload relay trip amperage to set the thermal overload in the motor starter.
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