What does cover mean in Table 300.5?

Cover is the shortest distance measured in inches between the top of the buried raceway or cable and the top of the finished grade, concrete, or other surface. It is not the trench depth to the bottom of the conduit.

Why does PVC get less cover than direct burial?

Rigid raceways protect the conductors mechanically, so the code allows shallower minimum cover than for an unprotected direct-buried cable. Rigid and intermediate metal conduit get the least required cover because they are the most robust.

Can a concrete slab reduce required cover?

Yes. NEC Table 300.5 notes allow reduced cover where the run is under at least 2 inches of concrete or equivalent, and residential 120 V GFCI-protected branch circuits of 20 A or less also get a reduced minimum. This tool applies the table column you select.

Does this cover over 600 volt circuits?

Yes. Table 300.5 historically covered 0 to 600 V, with over 600 V in Table 300.50. Recent code editions revised the threshold to 1000 V, but the depth values are unchanged in practice. Select the high-voltage option for the deeper requirements.

Is the local utility or AHJ the final word?

Yes. The NEC sets minimums, but the authority having jurisdiction and the serving utility can require deeper burial, warning tape, or encasement. Always confirm the local amendments before trenching.

Underground Conduit Burial Depth Checker (NEC 300.5)

Trench too shallow and you fail inspection or risk a strike; trench too deep and you waste labour. This checker reproduces NEC Table 300.5, which sets the minimum cover for underground wiring by method, surface condition, and voltage. Pick the three inputs and it returns the code minimum in inches.

How it works

The NEC organizes minimum cover into columns by wiring method and rows by surface condition. The deeper the method needs protection, the greater the cover. The key column values for 0 to 600 V are:

                              Direct  RMC/IMC  PVC/other
                              bury    metal    nonmetallic
General earth                  24       6        18
Under 4 in concrete (resid)    18       6        12
Under road / vehicular         24      24        24
Under a building                0       0         0  (in raceway only)
1-/2-family driveway           18      18        18
GFCI residential branch ≤20A   12       6         6

Over 600 V runs require deeper cover (for example 30 inches direct-buried under general earth). This tool returns the matching cell for your selected method, surface, and voltage.

Example and notes

A PVC feeder under a general earth lawn at 240 V needs a minimum of 18 inches of cover. The same run under a driveway needs 18 inches, and crossing under a public road it jumps to 24 inches. Remember the value is cover to the top of the conduit, so dig the trench deeper than the cover by the outside diameter of the raceway. The serving utility and your local AHJ may require more, plus warning tape above the run.