CSLB C-10 Electrical ContractorWiring Methods and MaterialsEasy
A UF cable supplies a 120V, 20A GFCI-protected branch circuit to a detached storage shed. The cable does not run under a driveway or area subject to vehicular traffic. Per NEC Table 300.5, what is the minimum required burial depth?
- A6 inches
- B24 inches
- C18 inches
- D12 inches
Show answer & explanationAnswer & explanation
Correct answer: D. 12 inches
NEC Table 300.5 permits a reduced burial depth of 12 inches for direct-buried cables on 120V or less branch circuits protected by GFCI with a maximum 20A rating. Without GFCI protection, the standard direct burial depth for cable would be 24 inches.
Why the other options are wrong
- A. 6 inches is only permitted under specific conditions like rigid nonmetallic conduit encased in concrete.
- B. 24 inches is the standard depth without the GFCI exception.
- C. 18 inches applies to rigid conduit without concrete encasement in some cases, not this scenario.
UF Cable Burial Depth Exception
NEC Table 300.5 reduces minimum burial depth to 12 inches for 120V, 20A-or-less circuits protected by GFCI.
- Standard direct burial depth is 24 inches
- GFCI + 20A max reduces depth to 12 inches
- Depth measured from top of cable to finished grade
Memory trick: GFCI digs a shallower hole—only 12 inches deep