To solve for motor amperage, select values below  
This calculator is intended for use in sizing thermal overloads for squirrel cage type motors, running at speeds usual for belted motors and motors with normal torque characteristics. The voltages listed are rated motor voltages. The currents generated by our tool should be accurate for system voltage ranges of 110 to 120, 220 to 240, 440 to 480, and 550 to 600 volts.

These values are given only as a guide ? they may vary depending on the type of motor and manufacturer. Refer to the actual motor nameplate for full-load current values. Motors built for low speeds (1200 rpm and less) or high torques may require more running current and multi-speed motors will have full-load current carrying varying with speed.

HP Voltage Phasing Motor Amperage
Single Phase

To obtain full- load currents for 200 and 208 Vac motors, increase corresponding 220 to 240 Vac ratings by 15 and 10 percent, respectively. To obtain full-load currents for 265 and 277 Vac motors, decrease corresponding 220 to 240 Vac ratings by 13 and 17 percent, respectively.  

Automatic recalculation