For piping larger than two inches in diameter, at least ___________ inches of horizontal service space shall be provided in front of the cleanout.

In the context of plumbing codes, especially regarding cleanouts for larger piping systems, the requirement for providing adequate horizontal service space is critical for maintenance and accessibility. For pipes larger than two inches in diameter, having at least 18 inches of horizontal service space in front of the cleanout is specified to ensure that plumbers have enough room to work effectively when performing inspections, cleaning, or repairs.

This space allows for proper access to the cleanout, facilitating the removal of blockages and ensuring that the cleanout can be operated without obstruction. It's essential for safety and efficiency, as inadequate space can hinder maintenance activities, potentially leading to emergencies or costly repairs in the plumbing system.

While other dimensions may be more generous or seem sufficient, the minimum requirement of 18 inches is rooted in practical plumbing standards designed to balance accessibility with space constraints in various installations. Thus, meeting this requirement ensures compliance with best practices in plumbing installations while ensuring that maintenance can be carried out safely and effectively.