IEC Special Occupancies and Equipment 3 — Questions and Answers
Question 1: What is the minimum burial depth for rigid metal conduit (RMC) under a parking lot?
- 6 inches
- 12 inches (Correct answer)
- 18 inches
- 24 inches
Correct answer: 12 inches
NEC Table 300.5 requires RMC to be buried at least 6 inches under a parking lot when not subject to vehicular traffic, but 24 inches in other cases—however under parking lots with vehicle traffic the minimum is 24 inches.
Question 2: In an agricultural building, equipment that is subject to water and corrosive vapors must be listed for use in:
- Dry locations only
- Damp or wet locations (Correct answer)
- Hazardous locations
- Class II environments
Correct answer: Damp or wet locations
NEC 547.5 requires electrical equipment in agricultural buildings exposed to water or corrosive vapors to be listed for damp or wet locations.
Question 3: What is the required clearance between a swimming pool and an overhead service drop conductor carrying up to 750 volts?
- 10 feet
- 14.5 feet
- 22.5 feet (Correct answer)
- 25 feet
Correct answer: 22.5 feet
NEC 680.8 requires a minimum horizontal clearance of 22.5 feet between a pool and overhead service conductors operating up to 750 volts.
Question 4: In a Class II hazardous location, the primary hazard is from:
- Flammable gases and vapors
- Combustible dust (Correct answer)
- Flammable liquids
- Explosive atmospheres from fibers
Correct answer: Combustible dust
Class II hazardous locations are defined by the presence of combustible dust that can ignite and create an explosive atmosphere.
Question 5: For a temporary power installation at a construction site, GFCI protection is required for all:
- 240-volt receptacles only
- 125-volt, 15- and 20-ampere receptacles (Correct answer)
- Receptacles over 30 amperes
- Three-phase receptacles
Correct answer: 125-volt, 15- and 20-ampere receptacles
NEC 590.6 requires GFCI protection for all 125-volt, 15- and 20-ampere receptacles on construction sites.
Question 6: Which NEC article covers marinas and boatyards?
- Article 553 (Correct answer)
- Article 553
- Article 553
- Article 553
Correct answer: Article 553
NEC Article 553 covers floating buildings, while Article 553 is actually for floating buildings—marinas and boatyards are covered by Article 553.
Question 7: In an anesthetizing location of a health care facility, electrical equipment must be:
- Rated for Class I, Division 1
- Listed for flammable anesthetizing locations (Correct answer)
- GFCI protected only
- Installed with isolated ground receptacles
Correct answer: Listed for flammable anesthetizing locations
NEC 517.61 requires equipment in flammable anesthetizing locations to be specifically listed and approved for those hazardous conditions.
IEC Special Occupancies and Equipment 3
What is the minimum burial depth for rigid metal conduit (RMC) under a parking lot?