E2 Hazardous (Classified) Locations 2 — Questions and Answers
Question 1: In a Class I, Division 2 location, which wiring method is generally acceptable?
- Rigid metal conduit (RMC) (Correct answer)
- Type NM cable
- Open wiring on insulators
- Type SE cable
Correct answer: Rigid metal conduit (RMC)
Rigid metal conduit is an approved wiring method for Class I, Division 2 locations per NEC Article 501.
Question 2: Which NEC article covers Class II hazardous locations involving combustible dust?
- Article 500
- Article 501
- Article 502 (Correct answer)
- Article 503
Correct answer: Article 502
NEC Article 502 specifically addresses Class II locations where combustible dust is the hazardous material.
Question 3: What is the primary purpose of sealing fittings in Class I hazardous locations?
- To prevent moisture ingress
- To prevent the passage of gases, vapors, or flames (Correct answer)
- To support the conduit system
- To allow for thermal expansion
Correct answer: To prevent the passage of gases, vapors, or flames
Sealing fittings in Class I locations prevent the passage of gases, vapors, or flames from one portion of the electrical installation to another.
Question 4: A spray paint booth where flammable liquids are used would typically be classified as which hazardous location?
- Class I, Division 2
- Class I, Division 1 (Correct answer)
- Class II, Division 1
- Class III, Division 1
Correct answer: Class I, Division 1
A spray paint booth where flammable vapors are present during normal operations is a Class I, Division 1 location.
Question 5: In the Zone classification system, Zone 0 corresponds most closely to which Division classification?
- Division 1 only — continuous hazard (Correct answer)
- Division 2
- A combination of Division 1 and 2
- No direct equivalent exists
Correct answer: Division 1 only — continuous hazard
Zone 0 represents locations where ignitable concentrations of flammable gases or vapors are present continuously, corresponding to the most hazardous portion of Division 1.
Question 6: Aluminum conduit is permitted in Class I hazardous locations under which condition?
- Never; only steel conduit is permitted
- When specifically listed for the hazardous location (Correct answer)
- In Division 2 locations only
- When the trade size is 1 inch or larger
Correct answer: When specifically listed for the hazardous location
Aluminum conduit may be used in Class I hazardous locations when it is specifically listed for use in that hazardous location.
Question 7: Which of the following equipment markings indicates it is suitable for use in Class I, Division 1, Groups C and D locations?
- CL I DIV 1 GP C,D (Correct answer)
- EXd IIC T3
- Class I Zone 1 AEx d IIB
- NEMA 4X
Correct answer: CL I DIV 1 GP C,D
The marking 'CL I DIV 1 GP C,D' directly indicates the equipment is listed for Class I, Division 1, Groups C and D hazardous locations.
E2 Hazardous (Classified) Locations 2
In a Class I, Division 2 location, which wiring method is generally acceptable?