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:

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:

Comments?

Jim Elder
Ottawa, Canada

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