Does the NEC dictate the maximum depth inside a Christy/Oldcastle in-ground concrete electrical box? I looked at Section 110, Part V (Manholes and Other Electrical Enclosures Intended for Personnel Entry, All Voltages), but if it's there, I missed it.
We have a Christy box at the intersection of two conduit runs. The box is 35"W x 64.5"L. It currently consists of a formed-in-place concrete base that measures 12" deep inside, plus one extension ring that is 10" deep, plus a top ring that is 14" deep. The total depth is 36".
Sometime in the past, the surrounding grade was changed and the box was buried under 30" of soil. We plan to re-grade the area and lower the surrounding soil, but we'd also like to add more extension rings to raise the top of the box.
We have a Christy box at the intersection of two conduit runs. The box is 35"W x 64.5"L. It currently consists of a formed-in-place concrete base that measures 12" deep inside, plus one extension ring that is 10" deep, plus a top ring that is 14" deep. The total depth is 36".
Sometime in the past, the surrounding grade was changed and the box was buried under 30" of soil. We plan to re-grade the area and lower the surrounding soil, but we'd also like to add more extension rings to raise the top of the box.