E2 Special Occupancies 3 — Questions and Answers
Question 1: Under NEC Article 511, in a commercial repair garage, the area within 18 inches above floor level is classified as:
- Class I, Division 2 (Correct answer)
- Class II, Division 1
- Unclassified if ventilated
- Class I, Division 1
Correct answer: Class I, Division 2
NEC 511.3 classifies the area up to 18 inches above floor level in commercial garages as Class I, Division 2 due to heavier-than-air gasoline vapors.
Question 2: In an aircraft hangar per NEC Article 513, the area within 5 feet horizontally from aircraft power plants is classified as:
- Class I, Division 2 (Correct answer)
- Class I, Division 1
- Class II, Division 2
- Unclassified with proper ventilation
Correct answer: Class I, Division 2
NEC 513.3 classifies areas within 5 feet horizontally from aircraft power plants and fuel tanks up to 5 feet above the upper surface as Class I, Division 2.
Question 3: At a motor fuel dispensing facility (gas station), the space within the dispenser enclosure and within 18 inches horizontally in all directions from the dispenser is classified as:
- Class I, Division 2
- Class I, Division 1 (Correct answer)
- Unclassified above grade
- Class II, Division 1
Correct answer: Class I, Division 1
NEC 514.3 classifies the interior of the dispenser enclosure and the 18-inch zone around it as Class I, Division 1.
Question 4: In spray application areas covered by NEC Article 516, the zone immediately surrounding open containers of flammable liquids is classified as:
- Class I, Division 2 within 3 feet (Correct answer)
- Class I, Division 1 within 5 feet
- Class II, Division 1 throughout the booth
- Unclassified with local exhaust ventilation
Correct answer: Class I, Division 2 within 3 feet
NEC 516.3 classifies the area within 3 feet in all directions from open containers of flammable or combustible liquids as Class I, Division 2.
Question 5: Under NEC Article 511, electrical equipment in a pit or depression in a commercial garage floor is subject to which classification?
- Unclassified if sealed from below
- Class I, Division 2 throughout the entire pit
- Class I, Division 1 throughout the entire pit (Correct answer)
- Class II, Division 1 below floor level
Correct answer: Class I, Division 1 throughout the entire pit
NEC 511.3 requires pits and depressions in commercial garages to be classified as Class I, Division 1 because heavier-than-air vapors accumulate there.
Question 6: Which NEC article governs electrical installations in bulk storage plants where flammable liquids are stored in above-ground tanks?
- Article 513
- Article 514
- Article 515 (Correct answer)
- Article 516
Correct answer: Article 515
NEC Article 515 covers bulk storage plants, which include facilities where flammable liquids are stored, blended, or redistributed in above-ground tanks.
Question 7: In a commercial garage with adequate ventilation per NEC 511.3(B), the area above 18 inches from the floor is classified as:
- Class I, Division 1
- Class I, Division 2
- Class II, Division 2
- Unclassified (Correct answer)
Correct answer: Unclassified
When a commercial garage has adequate ventilation, the area above 18 inches from the floor is considered unclassified per NEC 511.3(B).
E2 Special Occupancies 3
Under NEC Article 511, in a commercial repair garage, the area within 18 inches above floor level is classified as: