Practice Test Geeks(E2) E2 Commercial Electrical Inspector Practice Test
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Sizing and Protection of Motor Circuits Flashcards

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  1. Per NEC 430.22, the minimum ampacity for branch circuit conductors supplying a single continuous-duty motor shall be what percentage of the motor's full-load current?

    Answer: 125% of FLA

    NEC 430.22 requires branch circuit conductor ampacity of at least 125% of the motor's FLA for continuous-duty applications.

  2. Which NEC table provides full-load current values for single-phase AC motors used for conductor and protection sizing?

    Answer: Table 430.248

    Table 430.248 lists FLA values for single-phase AC motors, which are used in place of nameplate values for conductor and overcurrent device sizing.

  3. A 5 HP, 230V, single-phase motor has a table FLA of 28A. What is the minimum required branch circuit conductor ampacity?

    Answer: 35A

    Minimum conductor ampacity = 125% × FLA = 1.25 × 28A = 35A per NEC 430.22.

  4. Per NEC 430.6(A)(1), which current value is used for sizing motor branch circuit conductors and short-circuit/ground-fault protective devices?

    Answer: Values from Tables 430.247 through 430.250

    NEC 430.6(A)(1) requires using table values from 430.247–430.250, not the motor nameplate, for conductor and short-circuit/ground-fault protection sizing.

  5. A 20 HP, 460V, 3-phase motor has a table FLA of 27A. What is the minimum branch circuit conductor ampacity required by NEC 430.22?

    Answer: 33.75A

    125% of 27A = 33.75A is the minimum conductor ampacity per NEC 430.22 for continuous-duty operation.

  6. Which NEC table provides full-load current values for 3-phase AC squirrel cage and synchronous motors?

    Answer: Table 430.250

    Table 430.250 provides FLA values for 3-phase AC motors, including squirrel cage and synchronous types, used for sizing conductors and overcurrent devices.

  7. Per NEC Table 430.22(E), motor branch circuit conductors for a 30-minute duty-rated motor must have an ampacity of at least what percentage of the motor's FLA?

    Answer: 150%

    NEC Table 430.22(E) requires 150% of FLA for branch circuit conductors supplying 30-minute and 60-minute duty-rated motors.