Appliance Watt Ratings
- Electricity use is most commonly measured in terms of watts, and the wattage rating on an appliance indicates how much electricity is used in the course of normal operation during one hour of use. Since some appliances might easily use thousands of watts of power in a single day, total electricity consumption is usually measured in terms of kilowatts (1 kilowatt = 1,000 watts). The other two standard measurements for electricity, volts and amperes, are more useful for engineering purposes than for measuring practical power consumption.
- To put the raw wattage rating of an appliance into perspective requires knowing a bit about wattage ratings across the board. A typical light bulb has a rating of 60 watts, while that of a clothes washer uses is 300 and 500 watts. Most televisions consume between 60 and 150 watts, and most personal computers use about 90 watts. Appliances that create heat, such as space heaters, hair dryers and clothes dryers, are very power-intensive and routinely have ratings above 1,000 watts. The wattage rating for an appliance is usually found on a label or plate which also indicates other electrical statistics and bears the stamp of Underwriters Limited (UL).
- To calculate household consumption, the average power consumption of every appliance in the house must be calculated first. The refrigerator is an easy one, since it runs steadily all day. If it consumes 725 watts, multiply that by 24 and the sum is the daily consumption (17,400 watts or 17.4 kilowatts). However, a hair dryer is usually used only once per day and for several minutes, so its real consumption is just a fraction of its wattage rating. If the hair dryer is used for five minutes once per day and has a rating of 1,500 watts, its real daily consumption is 125 watts. After determining the real consumption for each appliance or device in the house, add the watts together and divide that number by 1,000. This determines the household usage in kilowatt-hours (kWh), which is the statistic that appears on most electricity bills.
- In some applications, electricity is not the most efficient power source for a given appliance. As previously noted, heat-producing appliances frequently use large amounts of electricity. That makes them more expensive to operate than gas-fired alternatives. Water heaters, space heaters, ovens and other heat-producing appliances are almost always cheaper to operate when powered by natural gas or another fuel (such as propane) than electricity, excepting certain remote areas where that fuel must be trucked in at great expense.
