Question 160Steam Plants - Assistant Engineer

The correct answer is B) Low water level cutoff switch. The low water level cutoff switch is a critical safety device on auxiliary boilers that must be tested prior to lighting off the boiler. This switch is designed to automatically shut off the boiler's fuel supply if the water level drops below a safe operating level, preventing damage to the boiler from low water conditions. Ensuring this safety device is functioning properly is a crucial step before firing up the boiler. The other options are not directly related to the pre-lighting checks required for the auxiliary boiler. Automatic bottom blow valves, voltage output of the ignition transformer, and insulation resistance readings in the ignition system are not part of the mandatory safety checks for this specific task.