CSLB C-10 Electrical ContractorWiring Methods and MaterialsMedium
A client requests a new 20A, 120V branch circuit to an outdoor shed. The circuit will be protected by a GFCI circuit breaker. What is the minimum burial depth required for a Type UF cable directly buried under a driveway, if no other protection is provided?
- A6 inches
- B12 inches
- C18 inches
- D24 inches
Show answer & explanationAnswer & explanation
Correct answer: B. 12 inches
According to NEC Table 300.5, Column 4 (Circuits exceeding 20A or 120V, but not exceeding 480V and 30A or 120V with GFCI protection), direct burial under a driveway requires a minimum cover of 12 inches.
Why the other options are wrong
- A. This depth is typically for circuits 120V or less with GFCI protection in residential areas not under a driveway.
- C. This depth is usually for circuits not exceeding 600V where GFCI protection is not specified under a driveway.
- D. This depth is generally for circuits over 600V or in specific agricultural applications.
UF Cable Burial Depth
Type UF (Underground Feeder) cable, suitable for direct burial, has specific minimum cover requirements based on voltage, overcurrent protection, and location (e.g., under a driveway, residential property).
- Direct burial cable
- Requires specific cover depths per NEC Table 300.5
- GFCI protection can reduce required depth in some scenarios
Memory trick: Under Flow, find the right Footprint for buried wires.