TN LLE Wiring Methods and Installation 2 — Questions and Answers
Question 1: According to NEC 310.10(H), conductors connected in parallel must be what minimum size?
- 6 AWG or larger
- 4 AWG or larger
- 2 AWG or larger
- 1/0 AWG or larger (Correct answer)
Correct answer: 1/0 AWG or larger
NEC 310.10(H) permits conductors to be connected in parallel only if they are 1/0 AWG or larger.
Question 2: Per NEC Table 310.15(C)(1), when 4 to 6 current-carrying conductors are bundled together in a raceway, the ampacity must be derated to what percentage of the base table value?
- 50%
- 60%
- 70%
- 80% (Correct answer)
Correct answer: 80%
NEC Table 310.15(C)(1) requires an 80% derating factor when 4 to 6 current-carrying conductors are bundled in the same raceway.
Question 3: According to NEC 330.30, Type MC cable must be secured at intervals not exceeding:
- 4 feet
- 4.5 feet
- 6 feet (Correct answer)
- 8 feet
Correct answer: 6 feet
NEC 330.30 requires Type MC cable to be supported and secured at intervals not exceeding 6 feet.
Question 4: Under NEC 358.30, EMT (Electrical Metallic Tubing) must be secured at intervals not exceeding:
- 6 feet
- 8 feet
- 10 feet (Correct answer)
- 12 feet
Correct answer: 10 feet
NEC 358.30 requires EMT to be secured at least every 10 feet and within 3 feet of each outlet box, junction box, or other enclosure.
Question 5: Under NEC 350.60, Flexible Metal Conduit (FMC) is permitted to serve as the sole equipment grounding conductor only if the total ground return path length does not exceed:
- 3 feet
- 6 feet (Correct answer)
- 8 feet
- 10 feet
Correct answer: 6 feet
NEC 350.60 permits FMC to serve as the equipment grounding conductor if the ground return path length does not exceed 6 feet and the circuit overcurrent device does not exceed 20 amperes.
Question 6: Which of the following best describes a permitted use of Liquidtight Flexible Nonmetallic Conduit (LFNC) per NEC Article 356?
- Lengths up to 6 feet where flexibility or protection from liquids is needed (Correct answer)
- Unlimited lengths in exposed outdoor applications
- As a service entrance conduit on building exteriors
- In lengths exceeding 6 feet in concealed ceiling spaces
Correct answer: Lengths up to 6 feet where flexibility or protection from liquids is needed
NEC 356.10 permits LFNC in lengths up to 6 feet where flexibility or protection from liquids, vapors, or solids is required.
Question 7: When a conduit exits a concrete floor slab, NEC 300.4(F) requires that conductors be protected from abrasion by:
- A listed bushing or equivalent protection at the point where the conduit exits (Correct answer)
- Using only rigid metal conduit for all floor penetrations
- Extending the conduit at least 12 inches above the finished floor
- Installing a locknut below the floor surface
Correct answer: A listed bushing or equivalent protection at the point where the conduit exits
NEC 300.4(F) requires a listed bushing or equivalent protection where conductors emerge from conduit at floor level to prevent abrasion damage.
TN LLE Wiring Methods and Installation 2
According to NEC 310.10(H), conductors connected in parallel must be what minimum size?