The main objective of this project is to provide uninterrupted power supply to a load, by selecting the supply from any source out of 4 such as mains, generator, and inverter and solar automatically in the absence of any of the source. The demand for electricity is increasing every day and frequent power cuts is causing many problems in various areas like industries, hospitals and houses. An alternative arrangement for power source is a must. In this project uses four switches to demonstrate the respective failure of that power supply. while any of the switches is pressed it indicates the absence of that specific supply, switches are linked to microcontroller as input alerts. A microcontroller of 8051 own family is used. The output of microcontroller is given to the relay motive force IC, which switches suitable relay to preserve uninterrupted deliver to the load. The output shall be discovered the use of a lamp drawing electricity supply from mains initially. On failure of