Generac RTSN400G3 400-Amp Automatic Transfer Switch, 120/208V, 3-Phase (Discontinued by Manufacturer) Senses power failure and instructs your standby generator to start Maximum of 60,000-watts and compatible with standby generators from 20-60-kilowatts Nema 3r enclosure is suitable for outdoor applications 160-millisecond transfer time with a dual coil design Comes with a limited 2-year warranty