What is the UL Nominal Discharge Current (In) rating?

The UL Nominal Discharge Current is defined as the peak value of 8/20 microsecond surge current conducted through the SPD. The SPD must still function after 15 applied surges. The highest nominal discharge current rating by UL is 20kA. A SPD for use at the service entrance in UL 96A Lightning Protection Systems must be UL Listed and have a Nominal Discharge Current rating of 20kA.