What scenario requires the provision of combustion air according to NFPA 54?

The correct scenario that requires the provision of combustion air according to NFPA 54 is when the collective fuel input exceeds 1,000 BTU. NFPA 54 outlines the standards for the installation of fuel gas piping systems and emphasizes the importance of providing sufficient combustion air for appliances to operate safely and efficiently. When the fuel input exceeds the specified threshold, it indicates a potentially significant combustion process that necessitates proper ventilation to ensure the availability of adequate air for complete combustion. This helps prevent hazardous situations such as carbon monoxide poisoning or inefficient burning of fuel.

The other scenarios do not meet the requirements set by NFPA 54. For example, when the fuel input is less than 500 BTU, it is generally not deemed necessary to provide additional combustion air due to the relatively low fuel consumption not posing a significant risk. Additionally, the requirement for combustion air is not universally mandated for all residential buildings regardless of fuel input, nor is it limited to only commercial buildings; rather, it specifically applies based on the collective fuel input level. This targeted approach tailors safety measures to the actual demands of the fuel being used.