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Look up three-phase motor full-load current from NEC Table 430.250, plus the 125 percent conductor ampacity and 250 percent maximum breaker size.
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NEC 430.6 requires that conductor and overcurrent sizing for a motor use the full-load current value from Table 430.250, not the amps printed on the motor nameplate. The nameplate current is used only for overload protection. This calculator returns the table value for the horsepower and voltage you select.
Branch-circuit conductors for a single motor are sized at 125 percent of the full-load current under NEC 430.22. The branch-circuit short-circuit and ground-fault device, such as an inverse-time breaker, is generally allowed up to 250 percent of the full-load current under NEC 430.52, then adjusted to the next standard size if the motor will not start.
Conductor and breaker sizing come from the table full-load current. Overload protection, which guards the motor itself, is sized from the actual nameplate amps and the service factor. Keep the two separate to size a motor circuit correctly.
NEC Table 430.250 lists 15.2 amps for a 5 HP three-phase motor at 230 volts.
NEC 430.6 requires the table value for conductor and overcurrent sizing. The nameplate amps are used only for overload protection.
Branch-circuit conductors are sized at 125 percent of the table full-load current under NEC 430.22, then checked against ampacity and derating.
An inverse-time breaker is generally allowed up to 250 percent of the full-load current under NEC 430.52, rounded to the next standard size if needed for starting.
No. This uses the three-phase Table 430.250. Single-phase motors use Table 430.248, which has different values.