If you do any online shopping, you’ve probably run across ads for devices that claim to lower your monthly electric bill by helping you use less energy. These devices are labeled as “Power Savers” or “Electricity Savings Boxes”, among many other names.
The item descriptions sound great: Plug one of these power savers into an outlet (or, in some cases, have it hardwired into your electrical system), and voila—instant savings through reduced power usage. Sellers often claim these devices reduce power consumption by as much as 25%!
So what are these devices, really, and is there any truth to the sellers’ claims?
In the electrical world, these boxes are known as power-factor correction devices. They include a capacitor that helps deliver only the amperage that a device needs to function.
It's true that less amperage is delivered to the appliance, which can be useful in extending the life of appliances with less efficient designs. However, this would have no effect on residential consumer-members' bills, because the same amount of wattage —also known as “real power”—is being delivered to the home from the cooperative’s grid, and this wattage is the basis for billing.
What’s more, modern appliances with Energy Star certifications are already required to meet a certain power factor, meaning these devices are also unnecessary from the efficiency perspective.
A Pennsylvania news station performed a controlled test of a whole-home power-factor correction device in 2009 and recorded the results. Watch the power save results video.
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This article incorporates information from EDN and the Mapawatt blog.