Licensed Electrical Contractor Licensed Electrical Contractor Wiring Methods and Materials Questions and Answers 2 — Questions and Answers
Question 1: What is the maximum number of conductors permitted in a single raceway before derating factors must be applied according to NEC Table 310.15(C)(1)?
- 2 conductors
- 3 current-carrying conductors (Correct answer)
- 4 current-carrying conductors
- 6 current-carrying conductors
Correct answer: 3 current-carrying conductors
NEC Table 310.15(C)(1) requires ampacity adjustment when more than 3 current-carrying conductors are installed in a single raceway.
Question 2: Which wiring method is specifically required for circuits supplying fire pumps per NEC Article 695?
- Type NM cable
- Type MC cable listed for the application (Correct answer)
- Type UF cable
- Flexible metal conduit
Correct answer: Type MC cable listed for the application
NEC 695.6(B) requires wiring to fire pumps to be installed using methods that provide protection against physical damage, with listed Type MC cable being a specifically permitted method.
Question 3: What is the minimum burial depth for rigid metal conduit (RMC) installed under a one-family dwelling driveway?
- 6 inches
- 12 inches
- 18 inches (Correct answer)
- 24 inches
Correct answer: 18 inches
Per NEC Table 300.5, rigid metal conduit under a one-family dwelling driveway requires a minimum cover of 18 inches.
Question 4: When installing EMT in a wet location, what type of fittings must be used?
- Set-screw fittings
- Compression fittings listed for wet locations (Correct answer)
- Indenter fittings
- Any listed EMT fitting
Correct answer: Compression fittings listed for wet locations
NEC 358.42 requires fittings used in wet locations with EMT to be compression type listed as rainproof or suitable for wet locations.
Question 5: What is the maximum percentage of conduit fill permitted for three or more conductors installed in a raceway per NEC Chapter 9, Table 1?
- 31%
- 40% (Correct answer)
- 53%
- 60%
Correct answer: 40%
NEC Chapter 9, Table 1 limits conduit fill to 40% of the raceway's cross-sectional area when three or more conductors are installed.
Question 6: Which conductor material requires the use of an antioxidant compound at termination points?
- Copper
- Aluminum (Correct answer)
- Both copper and aluminum
- Neither copper nor aluminum
Correct answer: Aluminum
Aluminum conductors require antioxidant compound at connections to prevent oxidation that increases resistance and causes overheating at termination points.
Licensed Electrical Contractor Licensed Electrical Contractor Wiring Methods and Materials Questions and Answers 2
What is the maximum number of conductors permitted in a single raceway before derating factors must be applied according to NEC Table 310.15(C)(1)?