This read-write integer, expressed directly in volts (0-3120) with 0 meaning the limit is disabled, sets the voltage that the Y-Z phase-pair of circuit 1 can reach before the PDU triggers a warning notification, distinct from the harder yz1MaxVolt overvoltage limit. This earlier warning lets staff investigate a rising voltage trend on circuit 1's Y-Z leg while it is still a minor deviation rather than a full overvoltage event. For example, setting yz1WarnHiVolt to 240 volts would send a warning notification on Y-Z well before it reaches a 250V yz1MaxVolt cutoff.