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.

The lag pump must be set to start at a lower pressure than the lead pump to ensure it only activates during high-demand scenarios where the lead pump cannot maintain pressure. A 40 psig cut-in allows the lead pump to attempt to satisfy demand first before the lag pump engages.