Single-wall metal pipe shall not originate in any ___ and shall NOT pass through them:

Single-wall metal pipe is specifically not permitted to originate in or pass through concealed spaces due to safety and regulatory standards. Concealed spaces, such as walls or ceilings, can create hazardous situations because they can trap heat and potentially lead to a fire hazard if a leak or overheating occurs. This restriction is in place to ensure that any issues related to the metal piping can be easily identified and addressed, enhancing safety for both property and occupants.

While occupied spaces and unventilated areas also present concerns related to installation and safety, the most critical guideline focuses on concealed spaces where the pipe would be hidden, making monitoring and maintenance difficult. Therefore, recognizing that concealed spaces are particularly sensitive environments underscores why this is a crucial aspect of safety regulations for installations involving single-wall metal pipes.