A high idle switch sets a fire apparatus to idle at which range of rpm?

Answer: B — 900 - 1100 rpm

The high idle switch in a fire apparatus is designed to increase the engine's idle speed, allowing it to maintain sufficient power while operating auxiliary equipment or systems without the risk of stalling. The typical range for the high idle setting is between 900 and 1100 RPM. This range ensures that the engine provides adequate electrical output for lights, radios, and other equipment while still operating efficiently. Having this idle setting at 900 to 1100 RPM strikes a balance between fueling efficiency and the power needs of the apparatus, ensuring that the necessary systems function properly during fireground operations. This setting also helps to prevent the engine from running too rapidly, which can lead to unnecessary wear or potential overheating.