Class I and Class II SPDs are not enough to protect sensitive electronic elements. Overvoltage waves are slowly increasing at greater frequency, reoccurring and threatening devices. Incidence of low value surges are still too high for electronic elements and are common in the object itself, often caused by activation switching of major appliances, inductive devices and motors, or industrial System Operation failures. SPDs in this classification are intended to protect sensitve electronic installations in LPZ 2-3
per IEC 62305.