Sizing Motor Overcurrent Protection

9

Circuit overcurrent protection devices must be sized to protect the branch-circuit conductors and

also allow the motor to start without the circuit opening due to the in-rush current of the motor.

National Electrical Code Procedures

Use the NEC motor curr

Sizing Motor Overcurrent Protection

9

Circuit overcurrent protection devices must be sized to protect the branch-circuit conductors and

also allow the motor to start without the circuit opening due to the in-rush current of the motor.

National Electrical Code Procedures

Use the NEC motor current tables to find the design Full Load Current or FLA (adjusted for Service

Factor) unless it is not available.

C For Single Phase Motors: Use NEC Table 430-148

C For Three Phase Motors: Use NEC Table 430-150

• These values are about 10% higher than what a typical motor would draw at full load to

allow for bearing wear in the motor and load, etc.

C The values in the NEC tables will allow for replacement of the motor in the future without

having to replace the circuit conductors or overcurrent devices.

ent tables to find the design Full Load Current or FLA (adjusted for Service

Factor) unless it is not available.

C For Single Phase Motors: Use NEC Table 430-148

C For Three Phase Motors: Use NEC Table 430-150

• These values are about 10% higher than what a typical motor would draw at full load to

allow for bearing wear in the motor and load, etc.

C The values in the NEC tables will allow for replacement of the motor in the future without

having to replace the circuit conductors or overcurrent devices.