This standard defines general requirements, performance requirements, test methods, and marking for the following types of PVC plastic utilities duct. The PVC duct specified in this standard is intended for installation underground for communications and electrical wire and cable: Type EB-20 Designed for burial encased in concrete Type EB-35 Designed for burial encased in concrete Type DB-60 Designed for direct burial without encasement in concrete Type DB-100 Designed for direct burial without encasement in concrete Type DB-120 Designed for direct burial without encasement in concrete Type DB products can also used for concrete encased applications where specified. Fittings designed for use with the duct covered by these standards are described in NEMA Standards Publication No. TC 9, Fittings for PVC Plastic Utilities Duct for Underground Installation. NOTE -The values stated in U.S. customary units are to be regarded as the standard.