Licensed Electrical Contractor NEC General Requirements Questions and Answers 1 — Questions and Answers
Question 1: According to NEC Article 90, what is the primary purpose of the National Electrical Code?
- To provide design specifications for efficient electrical systems.
- To serve as an instruction manual for untrained persons.
- The practical safeguarding of persons and property from hazards arising from the use of electricity. (Correct answer)
- To guarantee the future expansion of electrical use in all installations.
Correct answer: The practical safeguarding of persons and property from hazards arising from the use of electricity.
NEC 90.1(A) explicitly states that the purpose of the code is the 'practical safeguarding of persons and property from hazards arising from the use of electricity.' It is not intended as a design manual or an instruction guide for those without proper training.
Question 2: An electrical panel is to be installed in a commercial building. The system is a 277/480V, 3-phase, 4-wire circuit. The wall opposite the panel is constructed of concrete block. What is the minimum required working space depth in front of the panel?
- 30 inches
- 36 inches
- 42 inches (Correct answer)
- 48 inches
Correct answer: 42 inches
Per NEC 110.26(A)(1) and Table 110.26(A)(1), for a system with a nominal voltage to ground of 151-600V (277V falls in this range), the minimum clearance for Condition 2 (exposed live parts on one side and grounded parts, such as a concrete block wall, on the other) is 3 feet 6 inches (42 inches).
Question 3: Which of the following best defines a 'Readily Accessible' location according to NEC Article 100?
- Capable of being reached by using a portable ladder.
- Guarded by a locked door that only qualified persons can open.
- Admitting close approach without the need for tools to open a panel.
- Capable of being reached quickly without climbing over or removing obstacles. (Correct answer)
Correct answer: Capable of being reached quickly without climbing over or removing obstacles.
NEC Article 100 defines 'Accessible, Readily (Readily Accessible)' as being 'Capable of being reached quickly for operation, renewal, or inspections without requiring those to whom ready access is requisite to climb over or remove obstacles or to resort to portable ladders, and so forth.'
Question 4: A contractor is installing service equipment in a commercial building (a non-dwelling unit). According to NEC 110.24, which information must be legibly field-marked on the equipment?
- The arc-flash hazard boundary.
- The name of the installing contractor.
- The maximum available fault current and the date the calculation was performed. (Correct answer)
- The short-circuit current rating of the panelboard.
Correct answer: The maximum available fault current and the date the calculation was performed.
NEC 110.24(A) requires that service equipment in other than dwelling units be legibly marked in the field with the maximum available fault current. This marking must also include the date the fault-current calculation was performed and be durable enough for the environment.
Question 5: Unless identified for use in the specific operating environment, NEC 110.11 prohibits the location of conductors or equipment in all of the following locations EXCEPT:
- In damp or wet locations.
- Where exposed to gases or fumes with a deteriorating effect.
- In areas with direct sunlight exposure. (Correct answer)
- Where exposed to excessive temperatures.
Correct answer: In areas with direct sunlight exposure.
NEC 110.11 addresses deteriorating agents. It prohibits placing conductors and equipment in damp/wet locations, where exposed to deteriorating gases/fumes/vapors/liquids, or where exposed to excessive temperatures, UNLESS they are specifically identified for such use. While direct sunlight can be a deteriorating agent, the code does not list it as a generally prohibited location without qualification; equipment must be suitable for the environment, which could include being sunlight-resistant if installed outdoors. The other options are explicitly mentioned as generally prohibited unless the equipment is specifically identified for that condition.
Question 6: When installing electrical equipment, the NEC requires that it be firmly secured to the surface on which it is mounted. Which section covers this general requirement?
- NEC 110.3(B)
- NEC 110.12(A)
- NEC 110.13(A) (Correct answer)
- NEC 110.22
Correct answer: NEC 110.13(A)
NEC 110.13(A), titled 'Mounting,' states that 'Electrical equipment shall be firmly secured to the surface on which it is mounted.' This is a fundamental requirement for safe and secure installations.
Licensed Electrical Contractor NEC General Requirements Questions and Answers 1
According to NEC Article 90, what is the primary purpose of the National Electrical Code?