The Generac 9951 is a 200 A, 120/240 V single-phase automatic transfer switch (ATS) designed for home and small commercial standby generator systems. Service‑rated, it can serve as a main disconnect in many installations. Built-in surge protection (SPD) guards against voltage spikes, and the switch uses open‑transition switching to ensure utility and generator power are never connected simultaneously. Enclosed in a NEMA 3R aluminum housing for outdoor or sheltered indoor use, it’s an all-in-one solution for seamless automatic backup power.