A 3.5-ton air-conditioning system typically uses around 3,500 watts, or 3.5 kilowatts, of power. This measurement refers to the system's cooling capacity and is based on the rate at which the AC can remove heat from a room. The actual power consumption may vary depending on the unit's efficiency, temperature settings, and usage patterns. It's advisable to check the specific power requirements mentioned on the AC unit or consult the manufacturer for accurate information.