PC - Professional Electrical Contractor Wiring Methods and Protection Questions and Answers

Question 1

According to NEC Article 240, what is the standard maximum overcurrent protection permitted for a 12 AWG copper conductor used in a residential branch circuit?

Accepted Answer

20 amperes

Answer

15 amperes

Answer

25 amperes

Answer

30 amperes

Question 2

An electrician is installing a feeder in a commercial building. The conductors will be run in a raceway where all conductors of the same circuit must be grouped together. Which NEC Article provides the general requirements for this installation practice?

Accepted Answer

Article 300

Answer

Article 240

Answer

Article 250

Answer

Article 310

Question 3

A new installation requires running Type UF cable underground to supply an outdoor receptacle. The circuit is 120V and protected by a 20A GFCI circuit breaker at its source. What is the minimum required burial depth for the Type UF cable under a residential lawn?

Accepted Answer

12 inches

Answer

6 inches

Answer

24 inches

Answer

18 inches

Question 4

Which of the following wiring methods is NOT permitted for use in a Class I, Division 1 hazardous location?

Accepted Answer

Electrical metallic tubing (EMT)

Answer

Threaded rigid metal conduit (RMC)

Answer

Threaded intermediate metal conduit (IMC)

Answer

Type MI cable with listed fittings

Question 5

In a commercial installation, a 400A feeder is tapped to supply a 100A panelboard. The tap conductors are 15 feet long and are installed in a raceway. According to the NEC feeder tap rules, what is the minimum required ampacity for these tap conductors?

Accepted Answer

133A (1/3 of feeder OCPD)

Answer

100A

Answer

40A (10% of feeder OCPD)

Answer

200A (50% of feeder OCPD)

Question 6

When installing conductors in parallel, which of the following is a requirement according to NEC 310.10(G)?

Accepted Answer

The conductors must be the same length, material, and size, and terminated in the same manner.

Answer

The conductors must be of different sizes to accommodate voltage drop.

Answer

The conductors can be made of different materials, such as copper and aluminum.

Answer

The conductors are only required to be the same length and material.