E2 Overcurrent Protection Devices 3

Question 1

Per NEC 240.4(B), using the next higher standard overcurrent device rating above the conductor's calculated ampacity is NOT permitted when the conductor ampacity exceeds:

Accepted Answer

800 amperes

Answer

NEC 240.4(B) prohibits rounding up to the next higher standard overcurrent device rating when the conductor ampacity exceeds 800 amperes; the OCPD must not exceed the conductor's ampacity.

Question 2

According to NEC 240.85, a circuit breaker with a straight voltage rating (e.g., 480V) is suitable for use in:

Accepted Answer

Either solidly grounded or ungrounded systems at that voltage

Answer

NEC 240.85 states that a straight voltage-rated circuit breaker may be applied in either solidly grounded or ungrounded systems at that voltage level.

Question 3

Per NEC Article 100, a current-limiting overcurrent protective device is defined as one that:

Accepted Answer

Reduces the let-through current to a value less than the available fault current

Answer

A current-limiting OCPD reduces the peak let-through current to a magnitude less than the maximum available fault current, reducing thermal and magnetic stress on protected equipment.

Question 4

Per NEC 240.24(E), in a multifamily dwelling, overcurrent devices protecting a specific dwelling unit shall be accessible to:

Accepted Answer

The occupant of the dwelling unit that is protected

Answer

NEC 240.24(E) requires that overcurrent devices protecting a dwelling unit be accessible to the occupant of that specific unit, allowing them to reset breakers without entering another tenant's space.

Question 5

Under NEC 110.9, equipment intended to interrupt current at fault levels must have an interrupting rating:

Accepted Answer

Sufficient for the nominal circuit voltage and the current available at its line terminals

Answer

NEC 110.9 requires that equipment intended to interrupt fault current have an interrupting rating sufficient for the nominal circuit voltage and the available fault current at its terminals.

(E2) E2 Commercial Electrical Inspector Practice Test

(E2) E2 Commercial Electrical Inspector Practice Test

E2 Overcurrent Protection Devices 3