Standby power is electrical power that a device consumes when not in present use, but plugged in to a source of power and ready to be used. Standby power consumption is the amount of such power that is used even though the power drainage is not apparent. The terms apply to appliances such as television sets, computers, computer peripherals, and various other devices, including those that use battery chargers. Standby power is expressed in watt s (W). An increasing number and variety of consumer devices incorporate standby features. Often a device is in standby mode when the consumer thinks it is completely powered-down. Placing the power switch in the OFF position does not guarantee that a device consumes no power. The only way an everyday consumer can be sure a device is not drawing power is to unplug it from the utility outlet. Standby power, over time, adds to the energy expense incurred by a household or business. Consider a home with the following appliances in standby operation: two television sets (10 W each); three cordless telephone s (2 W each); a computer with an Uninterruptible Power Supply (UPS), a scanner, external hard drive, compact disc (CD (24 W combined); and various other appliances such as microwave ovens, electric clocks, and hi-fi sets (20 W combined). The total standby power used by this household is 70 W. Over the course of a 365-day year, this amounts to more than 600 kilowatt hours (kWh). If electric energy rates average 8 cents per kWh for this period, the total bill for the year, resulting from standby power, is over 48 dollars. It can be argued that the economic cost of standby mode, for the average consumer, is worth the added convenience the feature provides in terms of shortened warm-up periods and well-charged batteries. But when the standby power of 70 W per household or business (often much more) is multiplied by millions in a nation and integrated over a long period of time, the resulting energy consumption may have far-reaching environmental and economic consequences