Journeyman Electrician Exam (NEC)Services, Feeders, and Branch CircuitsMedium
A service entrance conductor for a single-family dwelling is installed underground. The service is 200 amperes, 240V. What is the minimum depth of cover required for PVC conduit enclosing these conductors, where the voltage does not exceed 1000V, and no special conditions apply, according to NEC Table 300.5?
- A6 inches
- B18 inches
- C24 inches
- D12 inches
Show answer & explanationAnswer & explanation
Correct answer: B. 18 inches
According to NEC Table 300.5, for PVC conduit enclosing service entrance conductors of 1000V or less, without special conditions, the minimum cover requirement is 18 inches. The table provides different depths for various wiring methods and locations.
Why the other options are wrong
- A. 6 inches is for rigid metal conduit (RMC) or intermediate metal conduit (IMC) in certain residential applications, or under concrete slabs.
- C. 24 inches is for direct burial cables or raceways under roads/driveways, or for higher voltages.
- D. 12 inches is for nonmetallic raceways under buildings or 2-inch thick concrete, or for direct burial cables in specific situations.
Underground Wiring Cover Depth
The minimum depth of earth cover required for underground conductors and raceways, as specified in NEC Table 300.5, varies based on wiring method, voltage, and location.
- Protects against physical damage.
- Depths vary for direct burial, RMC, IMC, PVC.
- Special conditions (e.g., under roads, residential driveways) can alter depth.
Memory trick: Dig deep to keep wires safe from harm.