what is the minimum depth that medium voltage (13,200V) PVC conduits encased in concrete with 3 inches of concrete to the dirt from the conduit? is there a minimum? is the depth to the edge of the concrete or the edge of the conduit?
18 inches is correct for direct buried conduit. But see the Notes in Table 300.50. If this is within an industrial facility, I believe the cover can be reduced by 6" for each 2" of concrete over the conduit.