"Emergency Switch Board
As the name indicates, it supplies to equipment and machinery that are essential during any emergency like fire, flooding, etc. One important aspect about the emergency switch boards is that it is located above the load water line or the upper most continuous deck, where as the main generators and main switchboards are located below the weather deck or the load water line. Thus this ensures that the emergency supply is maintained when the vessel is flooded with water to the weather deck.
During normal operation, power is supplied from the main generators to the main switch board. The emergency switch board gets it supply from the main switch board. When the main generators fail, the main switch board looses its supply and this causes the emergency generator to start automatically, which will supply the emergency switchboard that is connected to various ship board auxiliaries. Thus critical equipment and machinery (essential services) are supplied always to maintain the safety of the ship and personnel."
The critical equipment includes 1 x Steering Motor, Main Fire Pump, Bridge Supply including nav + radio, power to Main Engines and Controlls.
Emergency Lighting etc.
Bob