The Southwire Surge Guard 50A 41261 Automatic Transfer Switch with full electrical protection is designed with dual 80A Chint contactors that include a mechanical interlock to ensure safe operation. The mechanical interlock design prevents both contactors from engaging at the same time when both power sources are available. The rugged plastic box provides a safe and secure enclosure for the transfer switch device. Avoid the potential of corrosion, sharp edges, and risk of an energized enclosure that comes with a metal box. The generator dominant configuration of the 41261 functions to always chose generator as the primary source power when it is available. The transfer switch automatically transfers power to the generator when both sources are available, after a 30 second delay. Once the generator is turned off and shore power is available, the 41261 will automatically transfer the source to shore power.• Shore power reverse polarity protection with LED and remote indicator• Shore power open ground protection with LED and remote indicator• High and low voltage protection with flashing LED indicator• Open neutral protection• Surge protection• Mechanical interlock with oversized dual contactor configuration• Generator dominant• UL/CUL 1008 listed• Measures 8.84"W x 12.75"L x 5.21"D Generator dominant configuration always choses generator as primary power source Automatically transfers power to generator when both sources are available Automatically transfers source to shore power once generator is turned off | Southwire 41261 50A 120V/240V Automatic Transfer Switch