What Is Your Power Requirement?
One of the most important things that you must know before buying a UPS is your “power requirement”. In simple words: What all electrical appliances (like CFL, tube lights, fan, television, computer, refrigerator etc.) will you run at the time of power cut. Power requirement is addition of the power consumed by various electrical appliances.
If the total current drawn by connected equipment exceeds the UPS system's capacity, the UPS becomes overloaded. If the UPS is overloaded, it will drop the load during an outage instead of switching to battery model.