Most standard residential underground electrical conduit needs about 18–24 inches of cover, but the exact depth depends on voltage, conduit type, and where it’s installed, and you must follow the NEC and local code, not just a rule of thumb.

Key depth rules (NEC-style overview)

  • For typical 120V residential circuits in nonmetallic (PVC) conduit in a yard or open ground, 18 inches of cover is a common minimum.
  • Direct-burial cable (no conduit) commonly requires about 24 inches of cover in open ground.
  • Under residential driveways or concrete slabs, minimum cover is often allowed to be shallower, around 12–18 inches depending on wiring method, because the slab provides extra protection.
  • Low‑voltage landscape lighting (30V or less) in conduit is typically allowed at 6 inches of cover.
  • Rigid metal conduit can often be as shallow as 6 inches in some locations, because the metal provides more mechanical protection.

In plain language: light‑duty, low‑voltage and metal raceways can be shallower; standard 120V branch circuits and direct‑burial cables usually must be deeper.

Typical depth ranges by situation

  • Open yard, 120V in PVC : Plan for at least 18 inches cover; many guides still advise 24 inches to be safely within code and out of shovel range.
  • Under residential driveway / parking : Often 18 inches minimum for conduit; some 120V GFCI‑protected circuits may be allowed at 12 inches, but only if they meet specific NEC conditions.
  • Under public streets / heavy traffic : Depths of around 24 inches or more are common because of vehicle loads and safety margins.
  • Low‑voltage control / landscape circuits (≤30V) : About 6 inches cover in many cases, with deeper requirements if under driveways/roads.

Local amendments can push these numbers deeper, especially in areas with frost heave or rocky soil.

Safety, permits, and inspections

  • Underground work is governed by the National Electrical Code (NEC) plus local code amendments, and inspectors rely heavily on NEC table 300.5 / 305 for burial depths.
  • Because the correct depth depends on voltage, wiring method, traffic loads, and whether the run is GFCI‑protected, professionals strongly recommend having an electrician or local inspector confirm the depth for your exact project before you dig or backfill.

Bottom line: For a quick mental rule, many homeowners use “about 18–24 inches for standard 120V outdoor circuits,” but the only safe and legal answer is whatever your current NEC edition and local code require for your specific wiring method, location, and voltage.

Information gathered from public forums or data available on the internet and portrayed here.