What the NEMA Size 4 rating means for fit
The AF145N4-3011-69: NEMA Size 4 defines the contactor's continuous current rating and physical envelope. In practice, this size handles motor loads in the range typical for a Size 4 starter — the exact ampere rating depends on the specific duty class (AC-1 resistive, AC-3 motor, etc.), but the NEMA frame ensures the contactor fits the same panel footprint and bus-bar spacing as other Size 4 devices. For a field-service swap, verify the coil voltage and auxiliary contact configuration on the nameplate match the existing installation before pulling the old unit.