CEP CEP National Electrical Code (NEC) & Code Compliance 1 — Questions and Answers
Question 1: Under the NEC, what is the minimum burial depth required for direct-buried 120/240V residential service conductors in a trench protected by conduit?
- 6 inches
- 12 inches (Correct answer)
- 18 inches
- 24 inches
Correct answer: 12 inches
NEC Table 300.5 requires a minimum burial depth of 12 inches for conductors installed in rigid metal conduit or IMC.
Question 2: According to NEC Article 210, what is the maximum length of a multiwire branch circuit extension cord allowed in a dwelling unit?
- The NEC prohibits multiwire branch circuit extension cords (Correct answer)
- 6 feet
- 10 feet
- 25 feet
Correct answer: The NEC prohibits multiwire branch circuit extension cords
The NEC does not permit multiwire branch circuits to be connected to extension cords; each circuit must be properly terminated.
Question 3: NEC 210.52 requires at least one receptacle outlet in each bathroom. What is the minimum ampere rating for such a receptacle?
- 15A
- 20A (Correct answer)
- 25A
- 30A
Correct answer: 20A
NEC 210.52(D) requires that at least one 20-ampere receptacle outlet be installed in bathrooms.
Question 4: Which NEC article governs the installation of conductors and equipment inside structures used for agricultural purposes?
- Article 547 (Correct answer)
- Article 550
- Article 555
- Article 560
Correct answer: Article 547
NEC Article 547 covers agricultural buildings and specifies wiring methods that resist the effects of moisture and corrosive atmospheres.
Question 5: Under NEC 230.70, the service disconnecting means must be located:
- Inside the electrical room only
- At the nearest accessible location to the service entrance
- Outside the building or nearest the point of entry inside (Correct answer)
- In a locked enclosure
Correct answer: Outside the building or nearest the point of entry inside
NEC 230.70(A)(1) requires the service disconnect to be installed outside or, if inside, nearest the point of entrance of the service conductors.
Question 6: According to NEC 250.122, if the overcurrent device protecting a circuit is doubled in size, what must be done to the equipment grounding conductor?
- It may remain the same size
- It must also be increased in size per Table 250.122 (Correct answer)
- It must be replaced with a bare conductor
- It must be grounded at both ends
Correct answer: It must also be increased in size per Table 250.122
NEC 250.122 requires that the EGC be sized based on the rating of the overcurrent device, so increasing the OCPD requires resizing the EGC per Table 250.122.
CEP CEP National Electrical Code (NEC) & Code Compliance 1
Under the NEC, what is the minimum burial depth required for direct-buried 120/240V residential service conductors in a trench protected by conduit?