In the event of grid failure islanding mode of operation of the electric generation unit is known as House load operation. Under this condition turbine generator produce only auxiliary load which is required to keep electric power plant unit alive. After restoration of grid the unit can be quickly synchronized back & load could be increased. I have following doubts about house load operation. Please share your knowledge & experience about this topic. 1. Have the machine supplied by major manufacturers in the world like Siemens, MHI, Alstom, GE, Skoda, Toshiba have House load capability? 2.Does the “House Load capability” of fossil fuel fired electric thermal unit has been demonstrated anywhere in the world? Has this test successful? If yes please provide unit reference where this test has been conducted. 3. How the boiler gets affected during house load operation of steam turbine generator? 4. What are the expected effects on the life of steam turbine generator of prolonged house load operation? 5. I believe for subcritical units under sudden large load rejection, unit gets tripped due to fluctuation of water level in drum. However for supercritical units drum gets replaced with separator. Can we say that house load operation can be easily demonstrated for supercritical units?