" ... Underground cable marking tape shall be installed a minimum of 6 in. (150 mm) and not more than 1 ft (300 mm) below finished grade for all underground conduit runs. When fiber optic cable is to be placed in the conduit, an underground cable marking tape with a metallic detection strip shall be used. Splicing of the tape shall be accomplished with metal clips to maintain electrical continuity along the entire length of the tape. Splices shall be wrapped with a waterproof adhesive tape."
" ... Underground cable marking tape shall be installed according to Article 810.04(a)."
"The tape shall be 6 in. (150 mm) wide; consisting of 7 mil (0.18 mm) minimum polyethylene according to ASTM D 882, ASTM D 5034, ASTM D 5035 and ASTM D 2103. The tape shall be red with black lettering or red with silver lettering reading “CAUTION – ELECTRICAL LINE BURIED BELOW”.
When specified, the tape shall be a woven reinforced polyethylene tape with a metallic core or backing that is detectable."