E2 Hazardous (Classified) Locations 3 — Questions and Answers
Question 1: Flexible connections in Class I, Division 1 locations must use which type of flexible fitting?
- Liquidtight flexible nonmetallic conduit
- Standard flexible metallic conduit
- Listed flexible fittings approved for the location (Correct answer)
- PVC-jacketed flexible conduit
Correct answer: Listed flexible fittings approved for the location
Flexible connections in Class I, Division 1 locations must use listed flexible fittings specifically approved for use in that classified location.
Question 2: In a Class II, Division 1 location, motors must be of which type?
- Totally enclosed fan-cooled (TEFC)
- Dust-ignition-proof (Correct answer)
- Explosion-proof
- Open drip-proof
Correct answer: Dust-ignition-proof
Motors in Class II, Division 1 locations must be dust-ignition-proof to prevent ignition of combustible dust accumulations.
Question 3: What is the maximum distance from a Class I, Division 1 or 2 enclosure that a conduit seal must be installed?
- 6 inches
- 12 inches
- 18 inches (Correct answer)
- 24 inches
Correct answer: 18 inches
NEC Section 501.15 requires conduit seals to be installed within 18 inches of a Class I, Division 1 or 2 enclosure.
Question 4: Which Group classification covers acetylene in Class I hazardous locations?
- Group A (Correct answer)
- Group B
- Group C
- Group D
Correct answer: Group A
Acetylene is classified in Group A, which represents the most sensitive and dangerous gas group in Class I locations.
Question 5: Intrinsically safe equipment is defined as equipment that:
- Is housed in an explosion-proof enclosure
- Cannot produce sparks or thermal effects capable of igniting a hazardous mixture (Correct answer)
- Uses pressurized enclosures to prevent hazardous atmosphere entry
- Is listed for Division 2 locations only
Correct answer: Cannot produce sparks or thermal effects capable of igniting a hazardous mixture
Intrinsically safe equipment is incapable of releasing sufficient electrical or thermal energy under normal or abnormal conditions to cause ignition of a specific hazardous atmospheric mixture.
Question 6: A grain elevator storage area with combustible grain dust would be classified under which Class and Group?
- Class I, Group D
- Class II, Group E
- Class II, Group G (Correct answer)
- Class III, Group F
Correct answer: Class II, Group G
Grain dust is classified as Class II, Group G, which covers agricultural dusts including grain, flour, and starch.
Question 7: In a Class I hazardous location, which type of luminaire (light fixture) is required in Division 1 areas?
- Vapor-tight luminaire
- Explosion-proof luminaire listed for Class I, Division 1 (Correct answer)
- Dust-tight luminaire
- Standard enclosed luminaire with GFCI protection
Correct answer: Explosion-proof luminaire listed for Class I, Division 1
Luminaires in Class I, Division 1 locations must be explosion-proof and specifically listed for Class I, Division 1 use.
E2 Hazardous (Classified) Locations 3
Flexible connections in Class I, Division 1 locations must use which type of flexible fitting?