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How To Reduce Electricity Bills by Turning off and Unplugging Devices

Stive has a 1st Class Honors Electronics Engineering degree including a high level math module and also masters level modules, from the O.U.

Electricity Meter with kWh Indicators

Electricity Meter with kWh Indicators

How You Buy Power

Electricity, similar to all things wholesale, retailed or auctioned, is priced 'per unit'. The unit for electricity charging is the kilowatt-hour, abbreviated kWh. A kilowatt is a thousand watts.

If you plug in a 1000-watt kettle and run it for an hour, you will be charged for 1 kWh, one unit of electricity. Read more about kilowatt-hours at the end of this article.

How You Consume Power

Power is consumed when a voltage is applied to a closed circuit and current flows. A closed circuit means that the current has a safe return path back to the supply.

We can say that Power (Watts) = Voltage Applied (Volts) x Current Flow (Amps).

Power cannot be consumed without current flow such as in an open circuit with an open or off switch. When there's no flow, Watts = Volts x 0 = 0.

A kettle or an electric fan, for example, does not consume any power when it is switched off, even though it remains plugged in to the mains supply outlet, because current cannot flow through the open switch. This is despite a qualified technician being able to dismantle the item and measure a voltage level at the input side of the on/off switch.

Other electric appliances, however, consume power even though they are seemingly powered off, due to them being in a ‘standby’ mode and not actually ‘off’.

How To Reduce Electricity Bills

Clearly we cannot control the cost of a kWh, which is set by the electricity company, and we cannot control the Watt rating of the items we already possess, which is set by the designer.

The only remaining factor that we do have control over is the time that we have the items switched on.

To reduce electricity bills, simply switch off items that are not in use—for example room lights in empty rooms—and try to reduce the time energy-consuming items are in use by disconnecting them from the electricity supply when they are no longer required.

Surprises Which May Shock You: Many Appliances That Aren't Running Consume Power

Several appliances in your home use power whenever they are plugged in, even when they are not being used: for example, washing machines that have completed their washing/drying cycle and phone chargers that are left plugged in when the phone is fully charged. These "phantom" appliances on standby only use pennies of electricity per day, but even two pennies a day is $/£7.30 in a 365-day year, and four is $/£14.60!

There are probably other items in your home consuming energy while they are switched on unnecessarily.

Leaving the TV set-top box or TV cable unit switched on overnight while we sleep for eight hours consumes quantities of electricity unnecessarily.

A simple 250W set-top/cable unit will consume 2kWh in an eight-hour sleeping session! That’s 730 wasted electricity units per year!

If an appliance does not have a master on/off switch on its rear panel to disconnect the mains entirely, then simply unplug it when you go to bed and leave it unplugged until you need to use it.

The TV, in standby mode, will not consume power at its full marked rating, but it is still consuming power nonetheless, so why not also switch that off at the rear panel master mains switch, or unplug it, until you need it.

A hint: Some household items are actually marked with an in-use Watt rating and a standby-mode Watt rating.

Electricity Pylons

Electricity Pylons

How Many kWh an Appliance Consumes, by Watt Rating and Running Time (Short Running Times)

Watt Rating2.5 mins5 mins7.5 mins10 mins20 mins30 mins

200

n/a

n/a

n/a

n/a

n/a

0.1

300

n/a

n/a

n/a

n/a

n/a

0.15

400

n/a

n/a

n/a

n/a

0.13

0.20

500

n/a

n/a

n/a

n/a

0.17

0.25

750

n/a

n/a

n/a

0.13

0.25

0.38

1000

n/a

n/a

0.13

0.17

0.33

0.50

1250

n/a

0.1

0.16

0.21

0.42

0.63

1500

n/a

0.13

0.19

0.25

0.50

0.75

1750

n/a

0.15

0.22

0.29

0.58

0.88

2000

n/a

0.17

0.25

0.33

0.67

1.00

2250

n/a

0.19

0.28

0.38

0.75

1.13

2500

0.1

0.21

0.31

0.42

0.83

1.25

Low Watt Rating, Low Running Time Means Low Energy Use

As can be seen in the above table, a low running time coupled with a low Watt rating consumes a very small number of kWh units. A medium power microwave of 1200W doesn't incur noticeable power use on your bill until around five minutes run time. High-power devices are the ones that use up a lot of kWh units in short time periods: kettles, room heaters, A.C. units, arc welders and similar.

How Many kWh an Appliance Consumes, by Watt Rating and Running Time (Long Running Times)

kWh1 hour2 hours3 hours4 hours6 hours8 hours

100

0.10

0.20

0.30

0.40

0.60

0.80

200

0.20

0.40

0.60

0.80

1.20

1.60

300

0.30

0.60

0.90

1.20

1.80

2.40

400

0.40

0.80

1.20

1.60

2.40

3.20

500

0.50

1.00

1.50

2.00

3.00

4.00

750

0.75

1.50

2.25

3.00

4.50

6.00

1000

1.00

2.00

3.00

4.00

6.00

8.00

1250

1.25

2.50

3.75

5.00

7.50

10.0

1500

1.50

3.00

4.50

6.00

9.00

12.0

1750

1.75

3.50

5.25

7.00

10.5

14.0

2000

2.00

4.00

6.00

8.00

12.0

16.0

2250

2.25

4.50

6.75

9.00

13.5

18.0

2500

2.50

5.00

7.50

10.00

15.0

20.0

How To Manage High-Watt Appliances with High Running Times

The above table shows that long running time coupled with a medium to high Watt rating consumes medium to high kWh units.

So take a look at high-watt-rated appliances, including anything that produces heat while running: TV set top or cable units, room heaters, electric fans, A.C. units, electric ovens, electric showers, clothes irons, high watt hair dryers, curling tongs, and anything that produces heat when running, These items should be operated for minimum necessary time and not left on unattended.

The refrigerator is unavoidably on 24/7, so choose a low-energy model, and keep the freezer section stocked because it runs more efficiently that way.

Electricity Bill

Electricity Bill

Typical Household Items: Watt Rating, Selected Run Times, Energy Use

Household Item or ApplianceTypical Watt RatingRun Time with / kWh ConsumedRun Time with / kWh Consumed

TV Set-Top or Cable Unit

220

4 hrs / 0.80 kWh

8 hrs / 1.60 kWh

Refrigerator

120

24 hrs / 2.88 kWh

24 hrs / 2.88 kWh

A.C. Unit

500

4.5 hrs / 2.25 kWh

9 hrs / 4.50 kWh

Microwave Oven

1200

3 mins / 0.06 kWh

6 mins / 0.12 kWh

Laptop PSU

300

3 hrs / 0.90 kWh

6 hrs / 1.80 kWh

Phone Charger

130

1 hr / 0.13 kWh

2 hrs / 0.26 kWh

Printer

45

30 mins / 0.02 kWh

1 hr / 0.05 kWh

Electric Fan

80

5 hrs / 0.40 kWh

10 hrs / 0.80 kWh

Electric Cooker 1 ring

1000

6 mins / 0.10 kWh

12 mins / 0.20 kWh

Kettle

900

30 mins / 0.45 kWh

1 hr / 0.90 kWh

Electric Shower

1000

6 mins / 0.10 kWh

12 mins / 0.20 kWh

Lamp / Bulb 1

40

4 hrs / 0.16 kWh

8 hrs / 0.32 kWh

Lamp / Bulb 2

60

4 hrs / 0.24 kWh

8 hrs / 0.48 kWh

Lamp / Bulb 3

100

4 hrs / 0.40 kWh

8 hrs / 0.80 kWh

Appliance Run Times Matter a Lot

As can be seen, even high-watt items with short run times do not consume a large number of kWh. Clearly a balance, or a compromise, is required to utilize gadgets and appliances at their optimum or peak efficiency without restricting the convenience or pleasure to have them and use them.

What, Exactly, Is a Kilowatt-Hour?

A lowercase k for kilo is a symbol from the International System of Units, commonly known as S.I. Units, and means 103 or 1000.

An uppercase W is also an S.I. unit and means Watt. A Watt is a unit of power or a quantity of energy transfer or flow or consumption in a given time period.

The power rating of electrical items and appliances is clearly written or marked on all household items such as kettles, heaters, microwave oven, TVs, toasters heaters, lamp bulbs, and many other common items.

A lowercase h is the S.I. unit for hour.

An imaginary Wh unit would be the number of Watts that an item would consume if it was operating or consuming power for an hour. For example, a 1000W kettle switched on for an hour would consume 1000 Wh.

1000 W x 1 h = 1000 Wh

A kWh is this imaginary Wh value divided by 1000 (kilo) to convert the figure to kWh. In the example, the 1000 Wh would convert to 1 kWh.

1000 W x 1 h ÷ 1000 = 1000 Wh / 1000 = 1 kWh

So you would be charged for 1 kWh, 1 unit of electricity, if you boiled a 1000W kettle for 1 hour (if it did not boil dry and overheat).

This article is accurate and true to the best of the author’s knowledge. Content is for informational or entertainment purposes only and does not substitute for personal counsel or professional advice in business, financial, legal, or technical matters.

© 2019 Stive Smyth

Comments

Stive Smyth (author) from Philippines on February 21, 2020:

Hi Brenda. I'm happy that my article was of use to you. Thank you for your comment.

Brenda Krupnow on January 27, 2020:

That was a very interesting article. For instance, I didn't know that a simple phone charger costs me .26 for 2 hours of use. Thank you so much and I will surely pass this on.

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