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Saving Electricity |
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How do I measure the amount of electricity something uses?[an error occurred while processing this directive]Remember that almost every device you can plug into the wall has a label or engraving that tells you how much energy it uses. (More on figuring energy use without directly measuring it.) But if you want to measure the energy use yourself, you can definitely do that too. There are four ways to measure how much electricity something uses: Let's look at the first three options in turn. (1) Buy a cheap, simple watt-hour meter
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What all this means is that you have to be sure to count
the beats. With a standard meter, beats and state changes
are the same thing, so it's easy. With a non-standard meter it's not.
With a non-standard meter like the one in the table, it's impossible to
count from beat 5 to beat 6, because you don't know when beat 7 starts.
With that meter you have start to start counting on beats 1, 2, 3, 4,
or 10.
An example using the calculator
Let's say you want to measure the energy used by your computer system.
STEP 1: We have a digital meter and we found the "1.0kH" on the meter. That's the default for the calculator, so we don't have to do anything here. If we found a different kH factor on the meter, we'd just plug that number into the calculator.
STEP 2: We decided to count how many seconds it takes for 10 beats. That'll give us pretty good accuracy.
STEP 3: We decided to use the "Read Twice" method because we didn't want to unplug and turn off every single thing in the house.
(a) To get started, we turn our computer ON, and turn the AC and the fridge OFF.
(b) We count our electric meter. It takes 177 seconds (nearly 3 minutes).
(c) We plug those numbers into the calculator (10 beats in 177 seconds)
(d) We turn the computer OFF.
(e) We go outside and count again. This time it's taking a long time for each beat and we're getting impatient, so we decide to count only 3 beats. It takes 194 seconds.
(f) We plug those numbes into the calculator (3 beats in 194 seconds), and we get the answer: 147 watts. Ta-da!
Formulas
The calculator above is all you need, but here are the formulas if you prefer to crunch the numbers yourself.
Electric Meter Formulas
Meter type
Formula type
Formula for Wattage
Digital
Crude but fast
3600 ๗ number of seconds for one beat x kH factor
Accurate but slow
3600 x number of beats ๗ number of seconds x kH factor
(measure for as many seconds as you like)Analog
3600 ๗ number of seconds for 1 revolution x Kh factor
Many thanks to Steve, who worked in the meter shop of a utility company, for providing info for standard digital meters, and another Steve (Cook) who provided info for nonstandard digital meters.
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Now that you know how to measure electric usage and you understand terms like Kilowatt, let's find out How to Save on Cooling.
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©1998-2010 Michael Bluejay, Inc. All Rights Reserved. Unauthorized reprinting is prohibited
All advice is given in good faith. We're not responsible for any errors or omissions. Electricity can kill you; if you're not competent to work on your electrical wiring then hire a professional to do it. |
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