Licensed Electrical Contractor Wiring Methods and Materials 2 — Questions and Answers
Question 1: What is the maximum number of 90-degree bends permitted in a single run of rigid metal conduit (RMC) between pull points?
- Two 90-degree bends
- Three 90-degree bends
- Four 90-degree bends (Correct answer)
- Five 90-degree bends
Correct answer: Four 90-degree bends
NEC 358.26 and 344.26 limit conduit runs to the equivalent of four quarter bends (360 total degrees) between pull points, outlets, or junction boxes.
Question 2: Which wiring method is permitted for use in a Class I, Division 1 hazardous location?
- Type NM cable
- Rigid metal conduit (RMC) (Correct answer)
- Type AC cable
- Electrical metallic tubing (EMT)
Correct answer: Rigid metal conduit (RMC)
NEC Article 501 requires threaded rigid metal conduit or Type MI cable in Class I, Division 1 hazardous locations.
Question 3: When installing Type UF cable underground, what is the minimum burial depth required for a residential branch circuit rated at 120 volts?
- 6 inches
- 12 inches
- 18 inches (Correct answer)
- 24 inches
Correct answer: 18 inches
NEC Table 300.5 requires Type UF cable to be buried a minimum of 24 inches, but under a dwelling unit the depth is 18 inches.
Question 4: Electrical metallic tubing (EMT) is NOT permitted to be used in which of the following locations?
- Dry locations exposed to view
- Concrete encasement in wet locations (Correct answer)
- Concealed in walls of commercial buildings
- Supported on open cable trays
Correct answer: Concrete encasement in wet locations
NEC 358.10 prohibits EMT where subject to severe physical damage or where embedded in concrete in wet locations; RMC or IMC is required instead.
Question 5: What is the minimum size of equipment grounding conductor required for a circuit protected by a 60-ampere overcurrent device using copper conductors?
- 14 AWG
- 12 AWG
- 10 AWG (Correct answer)
- 8 AWG
Correct answer: 10 AWG
Per NEC Table 250.122, a 60-ampere overcurrent device requires a minimum 10 AWG copper equipment grounding conductor.
Question 6: Type MC cable installed in a cable tray must be secured at intervals not exceeding how many feet?
- 3 feet
- 4 feet
- 6 feet (Correct answer)
- 8 feet
Correct answer: 6 feet
NEC 330.30 requires Type MC cable to be secured at intervals not exceeding 6 feet when run horizontally in a cable tray.
Question 7: Which of the following conductors is approved for direct burial without conduit?
- Type THHN
- Type XHHW
- Type UF (Correct answer)
- Type TW
Correct answer: Type UF
Type UF (Underground Feeder) cable is specifically listed for direct burial per NEC 340.10.
Licensed Electrical Contractor Wiring Methods and Materials 2
What is the maximum number of 90-degree bends permitted in a single run of rigid metal conduit (RMC) between pull points?