What work volume is required for direct burial of communication optical cables

5 requires a minimum of 600mm (24 inches) of cover for direct-burial cable in most industrial plant locations. Under concrete slabs without vehicular traffic, 450mm (18 inches) is permitted. 5 and, for telecommunications applications, by Telcordia GR-20 and local jurisdiction requirements. The following depth standards apply to most industrial and utility installations: In geographic areas with frost. For conduit, measure to the top of the conduit; for direct burial cable, to the top of the cable. A sand bed, warning tape, or backfill choice does not by itself reduce the required cover — only the specific table entries and notes do (for example, the “in trench below 2 in. of concrete” row, o...