FREE TN LLE Overcurrent Protection Questions and Answers

Question 1

An electrician installs a 12 AWG copper branch circuit in a residential home.
According to NEC 240.4(D), what is the MAXIMUM standard size overcurrent protective device that can be used for this circuit?

Accepted Answer

20 A

Answer

15 A

Answer

25 A

Answer

30 A

Question 2

According to NEC Article 240, an overcurrent protective device (OCPD) must generally be located at the point where the conductors receive their supply. Which of the following is a permitted exception to this rule?

Accepted Answer

When installing feeder tap conductors under specific conditions.

Answer

When using supplementary overcurrent protection.

Answer

When the circuit is located in a damp location.

Answer

When the load on the circuit is continuous.

Question 3

An electrical circuit has a calculated load of 28 amps. The conductors have an ampacity of 35 amps. Per NEC 240.4(B), the 'next size up' rule is being applied. Which is the highest standard size overcurrent device from the list below that can be used?

Accepted Answer

40 A

Answer

25 A

Answer

30 A

Answer

35 A

Question 4

Which of the following scenarios describes an 'overload' condition rather than a short circuit or ground fault?

Accepted Answer

A circuit continues to operate, but with excessive current drawn by equipment connected to it, causing the conductor to heat up.

Answer

An ungrounded 'hot' conductor accidentally touches a metal junction box.

Answer

A power tool's cord is damaged, causing the hot and neutral wires to make contact.

Answer

Insulation between two conductors fails, allowing them to touch.

Question 5

A feeder is protected by a 200A circuit breaker. An electrician needs to make a 10-foot feeder tap from this circuit to supply a panelboard. What is the minimum required ampacity of the tap conductors?

Accepted Answer

10% of the feeder overcurrent device rating.

Answer

10% of the feeder conductor ampacity.

Answer

1/3 of the feeder overcurrent device rating.

Answer

The rating of the panelboard's main breaker.

Question 6

Supplementary overcurrent protective devices, such as a small fuse found inside an appliance, are permitted to be used for what purpose?

Accepted Answer

To provide limited, additional protection for specific appliances or luminaires.

Answer

To serve as the required branch-circuit overcurrent protection.

Answer

To protect conductors against short-circuits on a feeder.

Answer

To replace the need for a main service disconnect.

An electrician installs a 12 AWG copper branch circuit in a residential home.According to NEC 240.4(D), what is the MAXIMUM standard size overcurrent protective device that can be used for this circuit?

An electrician installs a 12 AWG copper branch circuit in a residential home.
According to NEC 240.4(D), what is the MAXIMUM standard size overcurrent protective device that can be used for this circuit?