NEC Special Occupancies & Equipment 2 — Questions and Answers
Question 1: Under NEC Article 501, what class and division applies to a location where flammable gas or vapor is present in quantities sufficient to produce explosive mixtures during normal operations?
- Class I, Division 1 (Correct answer)
- Class I, Division 2
- Class II, Division 1
- Class III, Division 1
Correct answer: Class I, Division 1
Class I, Division 1 covers locations where ignitable concentrations of flammable gases or vapors can exist under normal operating conditions.
Question 2: NEC Article 502 governs Class II locations. Which of the following materials defines a Class II hazardous location?
- Flammable gases
- Combustible dusts (Correct answer)
- Easily ignitable fibers
- Flammable liquids
Correct answer: Combustible dusts
Class II locations are hazardous because of the presence of combustible dust that may be suspended in the air.
Question 3: In a Class I, Division 2 location, which wiring method is NOT permitted by the NEC?
- Rigid metal conduit (RMC)
- Type MI cable
- Open wiring on insulators (Correct answer)
- Intermediate metal conduit (IMC)
Correct answer: Open wiring on insulators
Open wiring on insulators is not an approved wiring method for Class I, Division 2 hazardous locations under NEC Article 501.
Question 4: According to NEC Article 511, commercial garages used for repair and storage of vehicles require special electrical treatment up to what height above the floor?
- 6 inches
- 12 inches
- 18 inches (Correct answer)
- 24 inches
Correct answer: 18 inches
NEC 511.3 designates the area within 18 inches of the floor as Class I, Division 2 in commercial garages where flammable fuels are used.
Question 5: What does the NEC require for all 15- and 20-ampere, 125-volt receptacles in bathrooms of dwelling units per Article 210.8?
- AFCI protection
- GFCI protection (Correct answer)
- Tamper-resistant receptacles
- Surge protection
Correct answer: GFCI protection
NEC 210.8(A)(1) requires GFCI protection for all 15A and 20A, 125V receptacles installed in bathrooms of dwelling units.
Question 6: NEC Article 547 covers agricultural buildings. What special concern drives the unique wiring requirements in these structures?
- High ambient temperatures
- Excessive moisture, corrosive atmosphere, and presence of livestock (Correct answer)
- Presence of flammable gases from vehicles
- High-voltage equipment near workers
Correct answer: Excessive moisture, corrosive atmosphere, and presence of livestock
Agricultural buildings present unique hazards including excessive moisture, corrosive environments from animal waste, and physical damage risks near livestock.
Question 7: Under NEC Article 517 for healthcare facilities, a 'critical branch' of the essential electrical system supplies power to which loads?
- Life safety systems only
- General illumination and receptacles throughout the facility
- Task illumination, special receptacles, and fixed equipment in patient care areas (Correct answer)
- Elevators and fire alarm systems
Correct answer: Task illumination, special receptacles, and fixed equipment in patient care areas
The critical branch of the essential electrical system in healthcare facilities supplies task illumination, specific receptacles, and fixed equipment serving patient care areas.
NEC Special Occupancies & Equipment 2
Under NEC Article 501, what class and division applies to a location where flammable gas or vapor is present in quantities sufficient to produce explosive mixtures during normal operations?