Motors, Motor Controls, and HVAC Equipment
Motor branch circuits
Motor loads are calculated from tables, not nameplate, for standard motors: Table 430.248 (single-phase) and 430.250 (three-phase) give full-load current. Branch-circuit conductors are 125% of FLC. The branch short-circuit and ground-fault device comes from Table 430.52 (often 250% for an inverse-time breaker), sized up to the next standard rating if needed. Overload protection is sized from the motor nameplate and protects the motor, not the conductor.
Disconnects and controllers
A motor disconnecting means must be within sight of the controller and within sight of the motor, or capable of being locked open. The disconnect is normally rated at least 115% of the motor FLC. Motor control circuits, starters, and overloads must be listed for the application.
HVAC
Article 440 uses nameplate values. The branch-circuit conductor is based on the minimum circuit ampacity (MCA), and the overcurrent device may not exceed the maximum overcurrent protection (MOP). The nameplate is the authority; never substitute Table 430.250 values for a hermetic refrigerant compressor. A/C disconnects must be within sight and readily accessible.
Worked example
A 230 V single-phase compressor nameplate reads MCA 22 A and MOP 35 A. Use 10 AWG copper (35 A at 75°C) for the branch circuit and a 35 A breaker or fuse. Do not use 125% of the nameplate FLC and do not install a 40 A breaker just because the wire will carry it.