IEC Basic Electrical Standards 2 — Questions and Answers
Question 1: What is the minimum burial depth for rigid metal conduit (RMC) installed under a residential driveway?
- 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 12 inches under residential driveways.
Question 2: According to the NEC, what color must the grounding conductor be identified by?
- White or gray
- Green or bare (Correct answer)
- Black or red
- Orange or yellow
Correct answer: Green or bare
NEC 250.119 requires equipment grounding conductors to be green, green with yellow stripe, or bare.
Question 3: A 20-ampere, 125-volt receptacle outlet is required in which of the following bathroom locations per NEC?
- Only above the toilet
- Within 3 feet of the sink basin (Correct answer)
- At least 6 feet from any water source
- Only on GFCI-protected circuits
Correct answer: Within 3 feet of the sink basin
NEC 210.52(D) requires at least one receptacle within 3 feet of each sink basin in bathrooms.
Question 4: What is the maximum voltage drop recommended by the NEC for branch circuits serving general loads?
- 2%
- 3% (Correct answer)
- 5%
- 10%
Correct answer: 3%
NEC 210.19(A) informational note recommends keeping branch circuit voltage drop to 3% or less.
Question 5: Under the NEC, which conductor insulation type is rated for use in wet locations?
- THHN
- TW
- THW (Correct answer)
- NM-B
Correct answer: THW
THW insulation is rated for use in both dry and wet locations, unlike THHN which is dry-location only.
Question 6: What is the standard ampacity of a #12 AWG copper conductor with THHN insulation in a conduit with three current-carrying conductors?
- 15 amperes
- 20 amperes (Correct answer)
- 25 amperes
- 30 amperes
Correct answer: 20 amperes
NEC Table 310.12 lists #12 AWG THHN copper at 20 amperes for up to three conductors in a raceway.
Question 7: Which NEC article governs the installation of services, including service-entrance conductors?
- Article 200
- Article 230 (Correct answer)
- Article 250
- Article 310
Correct answer: Article 230
NEC Article 230 covers services, including service conductors, service equipment, and clearances.
IEC Basic Electrical Standards 2
What is the minimum burial depth for rigid metal conduit (RMC) installed under a residential driveway?