This standard defines general requirements@ performance requirements@ test methods@ and marki ng 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 be used for concrete encased applications where specified. Fittings designed for use with the ducts covered by this standard are described in NEMA TC 9 Fittings for Polyvinyl Chloride (PVC) Plastic Utilities Duct for Underground Installation. Note: The values stated in U.S. customary units are to be regarded as the standard.