If a cleaning opening size is not possible, openings shall be provided at intervals of _______.

If a cleaning opening size is not possible, openings shall be provided at intervals of _______.

• A. 8 ft.
• B. 10 ft.
• C. 14 ft.
• D. 12 ft.

Answer: (D)

Access to ductwork for cleaning is essential so that cleaning tools can reach all portions of the system. When a standard cleanout opening size can’t be used, you have to add openings so that no section of duct is farther than the allowed distance from an opening. The maximum interval is 12 ft, ensuring cleaning equipment can reach effectively along the entire run. Choosing a shorter interval (like 8 ft) would create more openings than required; a longer interval (such as 14 ft) could leave a duct segment that is too distant from an access point. The 12 ft standard balances practicality with effective cleaning access.

Access to ductwork for cleaning is essential so that cleaning tools can reach all portions of the system. When a standard cleanout opening size can’t be used, you have to add openings so that no section of duct is farther than the allowed distance from an opening. The maximum interval is 12 ft, ensuring cleaning equipment can reach effectively along the entire run.

Choosing a shorter interval (like 8 ft) would create more openings than required; a longer interval (such as 14 ft) could leave a duct segment that is too distant from an access point. The 12 ft standard balances practicality with effective cleaning access.