Rhode Island Journeyman Plumber Practice Exam 2025 - Free Journeyman Plumber Practice Questions and Study Guide

The correct frequency for installing cleanouts in horizontal drains and building sewers that are 6 inches in diameter or smaller is determined by the need for accessibility for maintenance and cleaning. According to plumbing codes and standards, a cleanout should be installed every 100 feet along the horizontal run of a drain line; however, when it comes to larger diameters or different configurations, this requirement can vary.

In the specific case of drains that measure 6 inches or smaller, the accepted standard allows for installations at intervals of up to 400 feet. This provides adequate access for potential blockages that may occur in longer runs of pipe, while also balancing the need for efficient installation. The reasoning behind this interval is to ensure that plumbers and maintenance personnel can effectively address any issues without excessive disruption or labor.

Additionally, local plumbing codes may influence the exact requirements regarding the positioning and number of cleanouts, but the general guideline is to provide effective and practical means for keeping the piping system clear.

The other options present intervals that either exceed the maximum allowed count or do not align with the general codes for installation practices, emphasizing the importance of adhering to standards established for plumbing systems.