TRC SURGE GUARD AUTOMATIC TRANSFER SWITCHES0Permanently install Surge Guard protection in your RV. Protects RV bumper to bumper from faulty park power. Due to the increased sophistication of high-end motorized coaches, the additional monitoring and diagnostic features plus the benefits of a transfer switch are a plus for some RV owners.0TRC SURGE GUARD 30 AMP BASIC AUTOMATIC TRANSFER SWITCH0Mechanical interlocking contactors. Time delay at power up. Transfers to generator power automatically when energized after 30 second delay. When both shore power and generator power are available, generator dominates after a 30 second delay. Once the generator is shut down, shore power activates after a 3-4 second delay."