Journeyman Electrician’s Exam Journeyman Electrician's Hazardous Locations 1 — Questions and Answers
Question 1: What type of hazardous material defines a Class I hazardous location?
- Combustible dust
- Flammable gases or vapors (Correct answer)
- Easily ignitable fibers
- Radioactive materials
Correct answer: Flammable gases or vapors
Class I locations are those where flammable gases or vapors may be present in quantities sufficient to produce explosive or ignitable mixtures.
Question 2: In a Class I, Division 1 location, ignitable concentrations of flammable gas exist:
- Only under abnormal conditions
- Under normal operating conditions (Correct answer)
- Only during maintenance shutdowns
- Only in outdoor environments
Correct answer: Under normal operating conditions
Division 1 means ignitable concentrations exist under normal operating conditions, during repair or maintenance, or due to equipment breakdown.
Question 3: Class II hazardous locations are defined by the presence of:
- Flammable gases
- Combustible dusts (Correct answer)
- Ignitable fibers or flyings
- Flammable liquids only
Correct answer: Combustible dusts
Class II locations are hazardous because of the presence of combustible dust that can form ignitable mixtures with air.
Question 4: Class III hazardous locations involve which type of hazardous material?
- Flammable vapors
- Combustible dust clouds
- Easily ignitable fibers or flyings (Correct answer)
- Explosive gases under pressure
Correct answer: Easily ignitable fibers or flyings
Class III locations are hazardous because of the presence of easily ignitable fibers or flyings that are handled, manufactured, or used.
Question 5: Which NEC article covers Class I hazardous locations using the Zone classification system?
- Article 500
- Article 505 (Correct answer)
- Article 510
- Article 516
Correct answer: Article 505
NEC Article 505 covers Class I, Zone 0, Zone 1, and Zone 2 hazardous locations as an alternative to the Division system in Article 500.
Question 6: In a Class II, Division 1 location, combustible dust is present:
- Only during equipment failure
- In suspension or dangerous accumulations under normal conditions (Correct answer)
- Only outdoors in open spaces
- Solely as settled deposits on surfaces
Correct answer: In suspension or dangerous accumulations under normal conditions
Division 1 for Class II means ignitable dust concentrations may be in suspension or form dangerous accumulations under normal operating conditions.
Question 7: A grain elevator storage area would most typically be classified as:
- Class I, Division 1
- Class II, Division 1 (Correct answer)
- Class III, Division 2
- Class I, Division 2
Correct answer: Class II, Division 1
Grain elevators contain combustible grain dust that is routinely suspended in air under normal operations, making them Class II, Division 1.
