Master Plumber Practice Exam

The allowed degree of a branch for a truly vertical drainage line is 60 degrees. This angle is specified in plumbing codes and guidelines to ensure that waste can flow freely and efficiently through the drainage system. At a 60-degree angle, the branch can adequately maintain the necessary velocity of the drain flow without causing buildup or obstructions. Such a configuration improves performance by allowing waste and water to move smoothly into the main drainage line.

This degree is also chosen to balance both vertical and horizontal components of the drain design, ensuring minimal resistance to flow due to gravity while preventing any issues with air venting or backflow. Using a more acute angle, like 15 or 22.5 degrees, would not support optimal drainage flow for items of typical waste size. Meanwhile, an angle greater than 60 degrees could lead to turbulent flow, increasing the chance of blockages. Hence, 60 degrees is the appropriate and code-compliant choice for branching off from a vertical drainage line.