The STV25K-24S is a DIN rail mount Surge Protective Device with high-quality transient diversion system designed to protect sensitive equipment from damaging transient voltage surges resulting from load switching, lightning strikes and other sources. The installer should perform the following steps to ensure a quality installation. Input and output ground terminals must be connected for proper operation. This grounding is not only required for safety, but also for equipment performance. Incorrect grounding can reduce or impede the operation of the unit.