When a 4 by 1-1/2 inch sanitary cross is used to connect two like fixtures, which of the following is required?

Using a 4 by 1-1/2 inch sanitary cross to connect two like fixtures necessitates the inclusion of a cleanout above or below the cross. This requirement is crucial for several reasons.

Firstly, cleanouts provide access to the plumbing system for maintenance and servicing, allowing plumbers to easily clear blockages or debris that may accumulate within the drainage system. This accessibility is particularly important in systems that connect multiple fixtures, as clogs can occur at various points.

In instances where there is a sanitary cross connecting two fixtures, positioning a cleanout allows for convenient access for snake or hydro jetting equipment to tackle any potential clogs formed at the cross, ensuring the effective operation of the sanitary system.

Furthermore, adhering to plumbing codes, such as the Omaha Plumbing Code, emphasizes the importance of facilitating proper drainage and maintenance, thus preventing future plumbing issues and ensuring the optimal performance of the fixtures involved.

The other options, which suggest limiting the length of the waste arms, do not address the critical maintenance aspect needed when connecting fixtures with a sanitary cross. Thus, the requirement for a cleanout is not only a best practice but a necessary component for efficient plumbing maintenance.