NEC Overcurrent Protection & Controls 2

Question 1

Per NEC 240.4(D), what is the maximum overcurrent protection for a 12 AWG copper conductor?

Accepted Answer

20 amperes

Answer

NEC 240.4(D) limits 12 AWG copper to a maximum overcurrent device of 20 amperes.

Question 2

What is the standard ampere rating immediately above 100 A in the NEC 240.6(A) list of standard fuse and circuit breaker ratings?

Accepted Answer

110 amperes

Answer

NEC 240.6(A) lists 110 A as the standard rating directly above 100 A.

Question 3

When the ampacity of a conductor does not match a standard overcurrent device rating, 240.4(B) generally allows what for circuits 800 A or less?

Accepted Answer

Using the next higher standard rating

Answer

NEC 240.4(B) permits the next higher standard overcurrent device rating for circuits 800 A and below under specified conditions.

Question 4

Per NEC 240.4(D), what is the maximum overcurrent protection for a 14 AWG copper conductor?

Accepted Answer

15 amperes

Answer

14 AWG copper is limited to a maximum 15-ampere overcurrent device.

Question 5

Overcurrent protection for conductors and equipment is provided to open the circuit if current reaches a value that would cause what, per 240.1?

Accepted Answer

An excessive or dangerous temperature in conductors or insulation

Answer

Per the 240.1 informational note, overcurrent protection limits current to prevent dangerous temperatures in conductors and insulation.

NEC Practice Test