DIY (do-it-yourself) Projects

Published on December 8th, 2014 | by Peter Young


How To Use A Watt Meter


You can use a watt meter to determine how much power appliances and other electronic devices are using around your home. This article will show you how, but with the caveat that some appliances, like refrigerators and Window Air Conditioners cycle through phases. The watt meter only provides a snapshot of electricity use at the exact moment it’s plugged in. However, these devices are exceptionally effective at measuring electricity used when a device is on, and when it’s powered off but still plugged in (referred to as vampire power).

Things you’ll need:

  • A Watt Meter
  • Any electronic device or appliance on a standard 120 volt line (with a standard plug)
  • 3 prong to 2 prong adapter (if the outlets in the home are 2 prong)

How to use a watt meter

Before proceeding, check out this quick video to see just how easy it is to use a watt meter to test vampire energy losses, plug loads, etc.:

1. Unplug your electronic device from your wall or power strip. You’ll need to have the watt meter plugged into your wall or power strip in order for it to work, so either find an empty plug or unplug the device you’d like to test.

2. Plug your watt meter into your wall outlet or power strip. Now that you’ve found or made an empty spot for your watt meter go ahead and plug it into either the wall outlet or power strip. Once you’ve done that you should start to see your watt meter turn on.

3. Plug your electronic device into your watt meter. Now that your watt meter is plugged in you’re ready to start testing your electronics. Go ahead and plug in your first electronic and watch your watt meter. Is it registering anything? If so (and your electronic device is turned off) than you’ve discovered what is known as vampire power. Now, go ahead and turn your device on. What does your watt meter read?

Depending on the type of watt meter you have there are several different ways you can view your findings. One is by simply seeing the actual wattage being consumed by your electronics. However, some watt meters will allow you to view your findings by both monthly and yearly cost (assuming the electronic device is running 24/7). At this point we’d recommend that you go from room to room in your home and check all your electronics to discover where you can be saving money.

0.0 to 0.5

Many times, a watt meter will read something odd, like one very common model that simply reads 0.0 to 0.5 watts when measuring some devices. This does not mean energy is being used at that moment–it simply means that the level of energy flowing through the device is small enough not to be measured accurately by the device. It may well be 0.5, or it may well be 0.

Typical Vampire Power Losses

Screen Shot 2015-01-21 at 5.10.26 PM

Graphic courtesy of Hawaiian Electric Company


If you’re looking for more ways to make your home energy efficient, be sure to check out our green home improvement projects: Green Living Ideas, after all, is a top 20 home improvement website!

Photos courtesy of Flickr Creative Commons (Watt Meter)

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About the Author

graduated from Pacific Lutheran University (PLU) with a degree in journalism and has made sustainability and eco-conscious living mainstays of both his professional and personal life. It was during his time at PLU that he began his journey with sustainability and it's what has led him to writing for Green Living Ideas. He currently resides in Honolulu and works for Pono Home, an energy efficiency company focused on reducing carbon emissions and promoting a healthier, greener lifestyle.

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