Interior duct piping must be labeled where?

Labeling interior duct piping is essential for maintenance, safety, and efficient identification of the ductwork system. The requirement to label at each floor level ensures that anyone working on, inspecting, or navigating through the building can easily locate and identify the ducts serving each specific level. This practice is important for understanding airflow patterns, troubleshooting issues, and conducting necessary maintenance operations.

Labeling solely at the entry point or exit point would not provide sufficient guidance for those who need to interact with the duct system at various points throughout the building. Furthermore, limiting labels to the attic space would neglect the critical need to identify ducts in other parts of the building where they are accessed or serviced, resulting in potential hazards or inefficiencies. Therefore, labeling at each floor level is the most comprehensive and practical approach.