Which type of PVC must be encased in concrete when used underground?

The correct choice refers to Type EB (Type 1) PVC, which is specifically designed for certain applications, including underground installations. When using this type of PVC piping underground, it is required to be encased in concrete to provide additional protection against physical damage and environmental factors.

The concrete encasement serves several purposes: it helps protect the pipe from potential crushing forces, physical impacts, and environmental conditions that may compromise the integrity of the piping over time. This requirement ensures that the installation remains secure and functions effectively without risk of failure due to external pressures.

In contrast, Schedule 40 and Schedule 80 PVC pipes do not have the same encasement requirement when installed underground, although they may have limitations on where they can be used. These schedules refer to the thickness and pressure rating of the pipes, rather than their specifications for underground use. Type DB (Type 2) PVC, while suitable for certain applications, does not fall under the same stringent requirements for concrete encasement as Type EB does. Understanding these distinctions is crucial for making proper decisions regarding materials and installation practices in underground applications.