EETC Wiring Methods 4 — Questions and Answers
Question 1: When running Type NM cable through a 2x4 wood stud, what is the minimum distance the cable must be from the edge of the stud before a nail plate is required?
- 1 inch
- 1¼ inches (Correct answer)
- 1½ inches
- 2 inches
Correct answer: 1¼ inches
NEC 300.4(A)(1) requires a steel nail plate or the cable must be at least 1¼ inches from the nearest edge of a stud to protect against fastener penetration.
Question 2: In an outdoor installation, which conduit type is permitted to be used above grade exposed to sunlight and weather?
- Type NM cable
- IMC with listed fittings (Correct answer)
- ENT (Electrical Nonmetallic Tubing)
- Type AC cable
Correct answer: IMC with listed fittings
Intermediate metal conduit (IMC) with listed fittings is suitable for outdoor, wet, and exposed-to-weather locations per NEC 342.10.
Question 3: What is the minimum support interval for rigid PVC conduit (Schedule 40) with a trade size of 1 inch?
- 3 feet
- 4 feet (Correct answer)
- 5 feet
- 6 feet
Correct answer: 4 feet
NEC Table 352.30 requires PVC conduit (1-inch trade size) to be supported at maximum 4-foot intervals.
Question 4: A common mistake when pulling wire through conduit is exceeding the maximum pulling tension. Which factor most directly limits this tension?
- Conduit material type
- Conductor insulation color
- Conductor cross-sectional area and fill ratio (Correct answer)
- Number of couplings in the run
Correct answer: Conductor cross-sectional area and fill ratio
Maximum pulling tension is determined by the conductor size (cross-sectional area) and the coefficient of friction, which relates to fill and conduit geometry.
Question 5: Type MC cable (Metal-Clad) is defined under which NEC article?
- Article 320
- Article 330 (Correct answer)
- Article 334
- Article 340
Correct answer: Article 330
NEC Article 330 covers Type MC (Metal-Clad) cable, including its construction, uses permitted, and installation requirements.
Question 6: What is required when a conduit run transitions from indoors to outdoors and then re-enters a building?
- A weatherproof junction box
- Sealing fittings to prevent condensation and gas entry (Correct answer)
- A ground fault circuit interrupter
- An expansion fitting
Correct answer: Sealing fittings to prevent condensation and gas entry
NEC 225.27 requires sealing fittings where conduit enters a building from outdoors to prevent moisture and gases from entering the structure.
Question 7: When installing conductors in parallel, what NEC requirement applies to all parallel conductors?
- They must be the same color
- They must be the same length, material, size, and insulation type (Correct answer)
- They must be installed in separate conduits only
- They must be at least #6 AWG or larger
Correct answer: They must be the same length, material, size, and insulation type
NEC 310.10(H) requires parallel conductors to be the same length, material, circular mil area, insulation type, and termination method to ensure equal current sharing.
EETC Wiring Methods 4
When running Type NM cable through a 2x4 wood stud, what is the minimum distance the cable must be from the edge of the stud before a nail plate is required?