Suppose the pressure switch used to control the "lead" potable water pump is set at 45 psig cut-in for pump start and 55 psig cut-out for pump stop. What would be an appropriate setting for the "lag" potable water pump?

Correct Answer: Option A — 40 psig cut-in for pump start and 55 psig cut-out for pump stop.

Lag pumps are set to start at a lower pressure than the lead pump to ensure they only activate during high-demand periods. A 40 psig cut-in allows the lag pump to assist the lead pump when the system pressure drops significantly, maintaining adequate pressure throughout the ship.