IEC Overcurrent Protection 2

Question 1

What is the maximum standard ampere rating for a fuse per NEC 240.6(A)?

Accepted Answer

600A

Answer

NEC 240.6(A) lists 600A as a standard ampere rating for overcurrent protective devices.

Question 2

Which type of fuse is designed to open on sustained overloads but NOT on normal motor starting currents?

Accepted Answer

Time-delay fuse

Answer

Time-delay (dual-element) fuses tolerate short-duration inrush currents while still protecting against sustained overloads.

Question 3

Per NEC 240.4(D), a 14 AWG copper conductor used for general-purpose branch circuits must be protected at no more than:

Accepted Answer

15A

Answer

NEC 240.4(D) limits overcurrent protection for 14 AWG copper conductors to 15A.

Question 4

A fusible disconnect that opens all ungrounded conductors simultaneously is described as which type of fuse?

Accepted Answer

Multi-pole

Answer

Multi-pole (multi-element) fuses interrupt all ungrounded conductors at once, preventing single-phasing on three-phase equipment.

Question 5

Where must an overcurrent device NOT be located per NEC 240.24(E)?

Accepted Answer

In bathrooms of dwellings

Answer

NEC 240.24(E) prohibits overcurrent devices in bathrooms of dwelling units, dormitories, and guest rooms.

IEC - Independent Electrical Contractors Practice Test