Under what condition may single-wall metal pipe vent connectors pass through ceilings, floors, or walls?

Single-wall metal pipe vent connectors may pass through ceilings, floors, or walls when permitted in accordance with NFPA 54, which is the National Fuel Gas Code. This code establishes safety regulations and requirements for the installation of gas appliances and their venting systems.

The reason this option is correct lies in the fact that NFPA 54 provides specific guidelines about the materials and clearances that must be maintained when venting appliances. It is crucial to adhere to these guidelines to ensure safety, preventing potential hazards such as fire or carbon monoxide leaks. The code specifies when and how vent connectors can safely pass through different construction elements in a building.

The other options do not align with the established safety standards as prescribed by NFPA 54. For instance, "by prior inspection only" implies a requirement that does not appropriately reflect the code's provisions, which detail specific conditions rather than making it solely reliant on inspections. Similarly, stating that connectors can pass "in any residential area" overlooks the necessary conditions outlined in NFPA 54 regarding location, construction, and clearances. Lastly, indicating that passing through these structures "when fitted with insulation" may create a misconception; insulation alone does not meet the comprehensive safety requirements without adherence to the guidelines set forth by