Running Costs of Domestic Electric Appliances
Electricity is sold by the unit. One unit is consumed by using electricity continuously at the rate of one kilowatt
(1 000 watts) for one hour. This means, for example, that one unit will allow a 100 W bulb to burn continuously
for 10 hours, a 250 W appliance will run for 4 hours and a 1kW (kilowatt) heater will deliver heat for 1 hour.
The following are close estimates; actual consumption will vary with models, condition of the appliance or its
age and circumstances of use.
The electrical Rand cost for each unit can be worked out from your electricity bill.
What you get for one unit:
Air conditioner (size & setting-dependent): 40 to 20 minutes
Bath: 1 x 25cm = 3 – 4 showers
Blanket (under): One week’s evening use
Blanket (over): 16 hours (2 nights)
Blender: 500 pints of soup
Can Opener: ± 6,250 cans
Carving knife: ± 220 joints
CD/DVD player (excluding speakers): ± 50 hours
Coffee percolator: 75 cups of coffee
Contact grill: 25 medium to well-done steaks
Cooker Hood: 10 hours
Extractor fan: 24 hours
Fan: ± 14 hours (size & setting-dependent)
Hair dryer: ± 3 hours
Hair rollers: 22 hair do-ups
Heater – fan 2 kW: 1/2 hour
Heater – convection: 2kW: 1/2 hour
Heater – oil-filled, 9 fins: 1/2 hour
Heater – wall panel, 250W: 4 hours
Heater – infra red 1 kW: 1 hour
Heater – radiant 3 kW: 20 minutes
Hi-Fi system (size-dependent): 6 -12 hours
Food mixer (stand model): Over 50 mixtures
Hot tray: 1/2 hours
Iron (hand): Over 2 hours
Kettle : ± 6 litres of water
Lawn trimmer (500W): 2 hours
Leaf blower (garden -2500W); 24 minutes
Light – incandescent 60 W bulb: 16,5 hours
Light – incandescent 100 W bulb: 10 hours
Light – twin 16W fluorescent tubes: 32 hours
Light – energy saving 18W (=100W): 55 hours
Microwave – 23 litres (800W): 1,25 to 2 hours
Power drill (250W): 4 hours
Radio: ± 20 hours
Refrigerator (compressor type): 24 hours
Shaver (electric) Over 1800 shaves
Slow cooking pot: 8 hours
Spin dryer: About 5 weeks’ laundry
Tape recorder: Over 24 hours
Television (colour CRT): ± 6 hours
Television (digital): ± 11 hours
Toaster: 70 slices of toast
Tumble dryer: ± 1/2 hour
Vacuum cleaner Model-dependent): 40 to 60 minutes
VCR: 55 hours
Waste disposal unit: ± 50 kg
Water heater – instant: ± 13 litres
Larger Appliances
Stove- per day for a family of 4: 2,5 to 3.5 units
Dishwasher, one full load: 2,5 units
Freezer (chest) – per week: 1,3 units per 25 litres capacity
Freezer (upright) – per week: 1,4 units per 25 litres capacity
Tumble drier: 20 minutes
Washing machine (±17 kg dry weight /week): 9 units
Washing machine (twin-tub) weight as above: 12 units.
Water heater – geyser: thermostat-setting & usage-dependent: to raise 100 litres
of water from 20oC to 60oC will use: ± 4,7 kW
Other:
Depending on configuration & operation:
Computer – desk top: 12 to 20 hours
CRT screen (19’ to 17’): 8 to 12 hours
Digital screen: 25 hours
Computer Laptop – battery charging: 10 to 12 hours worth of charges
Computer Laptop – on mains: 22 hours
8 N.B. Appliances on stand-by:
The International Energy Agency has determined that 15% of household electricity consumption worldwide
is used up by devices on stand-by. This will vary from country to country, and between households but we all
do tend to switch off appliances into stand-by modes, which still use between 5W to 15W, depending on the
appliance.
On average, an appliance on stand-by uses as much electricity as a medium-size domestic energy-saving
light bulb… Count the number of appliances you switch-off to stand-by (televisions, VCR, computers, HiFi;
each item averages 1 energy-saving light x 24 hours x 365 days a year, excluding the increase
in consumption when you do switch it on. Unless you use that appliance more than once a day or most of the
day, switch it off completely.
Note: a TV physically switched-off but plugged in (i.e. not on remote stand-by) will still allow for VCRs & DVD recorders to record from it.
