IEC Overcurrent Protection 4

Question 1

Per NEC 240.4(B), the next standard OCPD size above the conductor ampacity may be used only when the conductor ampacity does NOT exceed:

Accepted Answer

600A

Answer

NEC 240.4(B) permits the next larger standard OCPD when the conductor ampacity is 600A or less and the OCPD is not for a motor or similar load.

Question 2

Which Class of fuse has the highest interrupting rating and is designed for current-limiting service at 600V or less?

Accepted Answer

Class L

Answer

Class L fuses are rated 601A–6000A at 600V and carry a 200,000A interrupting rating, the highest available for standard fuses.

Question 3

Ground-fault protection of equipment (GFPE) per NEC 230.95 is required on solidly grounded wye services of more than 150V to ground but not exceeding 600V phase-to-phase when the service rating is at least:

Accepted Answer

800A

Answer

NEC 230.95 requires GFPE on services rated 800A or more on solidly grounded wye systems meeting the voltage criteria.

Question 4

When a circuit breaker is used as a service disconnect, it must be capable of being closed and opened by:

Accepted Answer

Manual operation

Answer

Per NEC 230.76, service disconnects must be capable of being operated manually.

Question 5

Per NEC 240.4(G), which conductor type is NOT permitted to have its overcurrent protection sized using the next standard rating above its ampacity?

Accepted Answer

Flexible cords

Answer

Flexible cords must be protected by an overcurrent device rated at or below the cord's ampacity per NEC 240.4(G).

IEC - Independent Electrical Contractors Practice Test

IEC - Independent Electrical Contractors Practice Test

IEC Overcurrent Protection 4