Minimum burial depths: 24" for direct burial cable, 18" for PVC conduit, 6" for RMC. Depths increase under driveways and decrease under building slabs. Understanding and complying with NEC 300. If you've ever had a. Today, we're diving deep into the world of distribution box grounding, breaking down the standards, and shining a light on those sneaky mistakes that even experienced electricians sometimes make. 5 (A); each of which specifies different burial depths that apply to the specific wiring methods named at the top of the column. 26 mm 2 (10 AWG) ground wire must be used, and in all other markets a 6 mm 2 must be used. To verify the adequacy of a new grounding system. Specify corrective steps, if any.