Power Consumption of Some Household Appliances

Oct 2006

Kill-A-Watt meter

How much power do typical household appliances consume? To find out, I used a "Kill-A-Watt" meter borrowed like a book from any branch of our Ottawa Public Library.

The Kill-A-Watt meter plugs into a power outlet, and then an appliance to be measured plugs into the Kill-A-Watt meter, as illustrated in the photo to the right. The power being consumed is displayed by the meter (59 watts, in the photo to the right).

The meter can also measure 'power factor' (for appliances containing motors) and energy consumption (kWh).

A watt (W) is a measure of power; power is energy per unit of time. 1 watt = 1 joule/second

A watt-hour (Wh) is a measure of energy. 1 watt-hour = 3600 watt-seconds = 3600 joules. Electrical energy is billed by the kilowatt-hour (kWh), ie., thousand watt-hours.

Thus a 60W traditional incandescent light bulb burning for 2 hours uses 2h * 60W = 120 Wh = 0.12 kWh of energy. One kilowatt-hour (kWh) costs about $0.06 in Ottawa today. That's cheap financially, but energy production has social & health costs that aren't included in that $0.06/kWh, such as air pollution (which is said to cause thousands of premature deaths annually in Ontario, and property damage, eg., due to acid rain). Just changing one light bulb (from ordinary incandescent to compact flourescent) in your house makes a difference.

Here's what I found out, using a Kill-A-Watt meter borrowed from the library:


DeviceWatts
Kettle1433
Microwave
Stand-by (clock)2
Running (high)1380
Refrigerator (old, replaced)
Idle0
Running114
Dehumidifier
Fan only47
Dehumidifying521
Vacuum cleaner753
Washing machine
Filling6
Agitating440
Pumping340
Spinning780
Fan ($75 'turbine' type)
Low57
Medium75
High97
Electric razor3
Stereo (old technology)
Off2
Normal volume24
Loud27
Stereo (new technology)
Off3
Normal volume11
Lamp
60W incandescent bulb63
Equiv compact flourescent bulb14
DeviceWatts
Piano (electric)
On, not being played13
Being played14
CD player2
Telephone
Off-hook0
Speakerphone1
Answering machine2
Laptop computer
Off, full charging50
Off, trickle charging27
Booting33
Windows (idle)23
Desktop computer
Off6
Memory test124
Windows (idle)78
Viewing DVD98
CRT computer display
Stand-by (computer off)2
1024x768 mode80
1600x1200 mode104
DSL modem + external router10
Laser printer
On, awaiting work14
Printing350
Battery charger9
Electric lawn mower550 to 720

The appliances that are the big electricity users (eg., range/ovens, clothes dryers, air conditioners, hot water heaters) have 240 VAC plugs, which are incompatible with the Kill-A-Watt meter. However, here are some rough estimates from the web:

DeviceWatts
Range/oven~7000
Clothes dryer~3000
Air conditioner~2500
Hot water heater~5000

Comments?

Jim Elder
Ottawa, Canada

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