What defines a confined space in terms of total input of gas-fired appliances?

A confined space in relation to gas-fired appliances is defined as having a total input of gas that is limited to specific volumes, which are set to ensure safety and proper ventilation. In this context, the correct definition is based on the total input capacity of gas appliances and how it relates to the volume of the space.

When evaluating confined spaces for safe operation of gas-fired appliances, understanding these volume limits is critical. The correct answer indicates that a confined space is one that has a volume of less than 50 cubic feet per thousand BTUs (British Thermal Units) of the total input of gas-fired appliances. This lower volume ensures that there is adequate ventilation to manage combustion gases safely, reduce the risk of a hazardous build-up of gases, and promote proper air exchange.

In larger volumes, such as 100, 200, or 500 cubic feet, the space could potentially provide insufficient ventilation, leading to unsafe conditions. The definition emphasizes the importance of maintaining safe operational conditions and protecting against risks associated with gas appliances in confined spaces.