How to read NEC Table 300.5 burial depth requirements

Reading the minimum cover table

Look up Table 300.5 in the free NFPA viewer. NFPA offers read-only access to current NEC editions at no cost. This page explains how to use the table; it does not reproduce it.

NEC Table 300.5 sets the minimum cover — the distance from the top of the cable or raceway up to finished grade — for underground wiring. Rows are locations (open ground, under concrete, under buildings, under roads and driveways, airport areas); columns are wiring methods. The more protection a method gives, the shallower it can go, and the more traffic a location sees, the deeper everything goes.

Worked example. A 240 V, 60 A feeder to a detached shop crosses a lawn and then the home’s driveway. In Schedule 40 PVC, the lawn section needs 18 in., and the one-/two-family driveway row also calls for 18 in. for PVC. Run the lawn section in RMC instead and the required cover drops a lot (check the RMC/IMC column in the free NFPA viewer). The 12 in. residential column doesn’t help here — the circuit is 240 V and over 20 A.

Second example. A 120 V, 20 A, GFCI-protected circuit to a yard post light at a house qualifies for the residential column: 12 in. of cover in open ground. Move that same run under a commercial parking lot and none of the shallow allowances apply — look up the street/parking row for the required depth.

Edition note: older editions titled this table for 0 to 600 V; the 2023 NEC covers up to 1000 V ac and moved higher-voltage installations to the new Article 305. The 2023 edition also revised the raceway column headings — check yours. For the conductors in the trench, start with the NEC 310.16 ampacity chart, apply correction and adjustment factors, check long runs with the voltage drop calculator, and size the raceway with the conduit fill chart. Field PM keeps trench photos and cover inspections with the daily report, so the depth is documented before backfill.