How Much is a Kilowatt?

The electrical energy you use at home has a price tag that reflects how smart you are about not wasting it.

In an era of concern for growing levels of carbon dioxide in the atmosphere, an increasing human population, and mounting uses for electricity, an old idea makes a new appearance. Conservation is a step everyone can take that will make a difference everywhere. The great thing is that there are many free ways to conserve as well as new tools that can help you conserve. Let’s consider how you can manage your use of electricity that helps your wallet, too.

Experiment Materials

• A residential electric meter

Experiment

1

Find the electric meter for your home and take a close look at it. Older model meters have a glass dome covering small, vertical black and white dials inside it. A large, horizontal moving dial will be very obvious. Some pointers on the smaller dials are likely moving while others aren’t. Newer meters may simply have digital displays and no moving dials.

On a house, the electric meter is usually outside near to where power lines come into the house from poles or from an underground cable. For an apartment complex or trailer park, several electric meters are often grouped together in one place. One meter should have your apartment or trailer number on it. (Be sure to get permission to see the meter.)

Look for the term “kilowatt-hour” (kWh) printed on the meter and think about what the moving dials (or changing digits) mean. (Think: “Money spent!”)

2

To get a better idea of how the meter works, look carefully at the meter with its changing numbers. Watch for ten seconds to get an idea of how fast they change. Go inside and turn on (or ask someone to turn while you watch the meter) a large, electric appliance like a vacuum cleaner, electric dryer, range, or oven. Watch the changing numbers on the meter for ten seconds and compare their speed now to your first check.

3

Shut off the appliance and check the meter again. The numbers have slowed way down as a result! The addition of any electrical device (lights included) moves the numbers to higher levels.

4

Even this not-very-scientific test shows that as you turn on and use lights and electric appliances in your home, the meter moves faster and the numbers go up. That means you’re using more electricity and the energy bill is getting larger.

How Does It Work

The meter you studied will help answer the question that started it all, “How much is a kilowatt?” Of course, there are many factors (time of day, season, etc.) that have to be considered to finally answer that but you do have to start with how many kilowatts are being used. The older style meters (analog) use a large, spinning, horizontal disk connected to smaller dials. It’s built in such a way that the disk spins faster as more electricity is pulled through the meter. As a result the smaller dials move faster as electrical energy consumption increases in the home. Digital meters are generally more precise and offer several options to both homeowners and power companies. They do, however, have temperature-related issues and sensitivity. In both cases, the numbers show how many kilowatt-hours have been used over a period of time.

Scottish scientist and steam-engine wizard, James Watt (1736–1819), introduced the term horsepower to the world. A “Watt” describes the power output needed to accomplish a task or to do work. The term “kilowatt-hour” (kWh or 1000 watts/hour) is used by electric companies to measure how much electrical “power” (electricity) you use at home each month. It’s a complicated calculation and that number is your monthly electric bill.

One kWh represents the amount of energy needed by a 1000-Watt device (such as a clothes iron or a microwave oven) to operate continuously for one hour. The US Energy Information Administration reports that, on average, a kilowatt-hour costs about \$.13 USD across the country.

Take It Further

People are sometimes clueless that electricity is not free and frequently demonstrate that fact by leaving doors open, lights on, and devices operating when not needed or no one is around. The electric meter doesn’t care and just keeps counting the kilowatt-hours (kWh) of electric power that pass through it. Monthly, it sends the amount used to the electric company where a dollar value is applied and you receive an electric bill.

It makes sense that a 100-watt bulb uses 100 watts of electricity. A desktop computer uses about 65 watts and a central air conditioner uses about 3,500 watts. Since all of the watts add up quickly, the term kilowatt is used to represent 1000 watts. To understand how much energy you’re using you also have to consider how long you run your appliances. When you use 1000 watts for an hour, that’s a kilowatt-hour. The key is to reduce the number of kilowatt hours you use each month in order to save money as well as natural resources.

How do you get a reduction? You can turn off lights and appliances that are not needed, do laundry in cold water instead of hot water (for electric water heaters), raise the thermostat temperature setting in the summer and lower it in winter, use a lower heat setting on a clothes dryer, purchase energy-saving appliances when possible, and use LED or CFL light bulbs instead of incandescent. You almost always get greater savings from simple conservation and smart usage of your electrical energy than from any other method.

Safety Information

It goes without saying that you’re involved with electricity here. Working around a meter and possibly an adjacent breaker box means there’s a whole lot more  power than what’s coming out of a wall outlet. That means a whole lot more caution is needed and touching unknown equipment or wires can be a very dangerous thing to do.