Massachusetts Plumbers Journeyman Practice Exam 2026 – All-in-One Guide to Master Your Licensing Test!

The required nominal size of cleanouts concerning the pipes they serve is indeed guided by plumbing codes, which dictate that cleanouts must be appropriately sized to facilitate effective access and maintenance of the drainage system. In Massachusetts, as in many other jurisdictions, the minimum size for cleanouts that serve pipes is typically aligned with the diameter of the pipe being serviced.

A nominal size of 4 inches is commonly established as the standard for cleanouts serving a variety of pipe sizes, particularly for those under 4 inches in diameter. This size ensures that there is enough access for rodding and cleaning without being overly large, which can complicate installation and maintenance. Having a cleanout that is too large compared to the pipe it serves can lead to unnecessary expense and may also affect the system's overall efficiency.

Consequently, 4 inches is the correct answer as it reflects the requirements laid out in relevant plumbing codes for effective operation while maintaining a standard across different pipe sizes, ensuring accessibility for clearing blockages.