Suppressed Voltage Rating. A series of discrete voltages used by UL to designate the performance of a surge suppressor. 330 volts is the lowest, (best), 400 volts is the next category, 500 volts is a third category. The SVR of a product to UL 1449 testing will likely be different from the SVR for the Adjunct Classification testing, since this UL 1449 Adjunct testing is at higher current levels, where the performance of a product may be different. When asking about SVR, be sure to specify whether the SVR is for UL 1449, or the UL 1449 Adjunct Classification testing.
Determined through testing by regulatory agency (UL, CSA, VDE, Etc.) or independent laboratory to specifications of IEEE/ANSI, IEC and UL. For permanently connected devices UL performs tests using a combination waveform 500 Amps/6000 volts.