Motor Overcurrent Protection Calculator

Electrical Calculator

Motor FLA & Conductor Size Calculator

Calculate estimated motor full-load current and minimum conductor size using motor power, voltage and phase, or enter a known FLA directly.

V
%
Efficiency and power factor are used only to estimate motor current. Use the motor nameplate or applicable Code table FLA when available.
A
Enter the applicable nameplate or Code-table motor current.

Conductor Settings

%
m
M

Ready to Calculate

Enter the motor information to calculate FLA and conductor size.

Recommended Conductor
Copper conductor
Motor input power
Motor full-load current
Conductor sizing factor
Minimum required ampacity
Selected conductor ampacity
Approximate voltage drop
Current calculation
Conductor calculation
The conductor was increased to meet the selected voltage-drop limit.
The required ampacity exceeds the conductor sizes included in this calculator. A parallel-conductor or engineered solution may be required.
Important calculation notes

HP/kW mode provides an estimated motor current using motor output power, efficiency and power factor. It is not a replacement for applicable Code-table current or motor nameplate information.

Conductor sizing is based on the selected motor-current multiplier and a built-in reference ampacity list. Correction factors for ambient temperature, conductor bundling, termination temperature, cable type, installation method and other Code requirements are not automatically applied.

The voltage-drop result is an approximate engineering calculation. Actual impedance, raceway arrangement, operating temperature and manufacturer data may affect the result.

This calculator does not determine overload settings, breaker or fuse size, controller rating, disconnect rating, bonding conductor size or short-circuit requirements.

Reference tool only: Verify all results against the current applicable electrical Code, equipment markings, approved drawings, manufacturer instructions and authority-having-jurisdiction requirements.