Definite scam!
Save up to 50% on your electric bill? Because of a device plugged into any outlet?
Uh, no.
Here's PG&E with a warning about "black box" energy savers: Before You Buy a Black Box
In the last few years I've noticed a huge "surge" :) in scam "electricity saver" products. Some are PFC capacitors, some are plans for "free energy" devices, some are ripoffs involving solar panels. Yours is just one of many, although this is the first time I've seen a claim that a surge protector can affect your KWH meter. And if it's actually a voltage regulator, then it needs to be wired into your fusebox panel. A regulator needs a series connection and cannot work by being plugged into an outlet.
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The old standby scam is to sell capacitors to homeowners, claiming that the AC motors in their appliances need correct power-factor. The scammers can get away with this because PFC power-factor correcting does actually save energy. Unfortunately the saved energy was all in the utility company power lines, not inside the home. The electric company will love you if you spend hundreds of bucks on a PFC capacitor. Their power lines run slightly cooler, and their generators use slightly less fuel. The higher current all remains between the capacitor and your various motors, so electric company is happy. But the scam part relies on customer ignorance: your KWH meter cannot detect the change. That's part of its design. Power-factor correction has zero effect on your KWH meter, so it won't actually save you a dime.
If you buy a fake "Power Saver," probably you'll see your electric bill actually go down. This is an interesting psychological effect: spending that much money makes you become waste-conscious about the electric utility. You'll start turning off lights, taking shorter showers, running dishwashers only when full. Doing all sorts of things to help reduce the bills. When it actually works, should we give credit to the magic scam box? Send testimonials to the advertisers? Instead try installing the device in someone elses' home, then don't tell them about it. Will it still work? Better yet, have a 3rd party do it without telling anyone which house has the device. To stop everyone from unconsciously helping it along, the only fair test is a double-blind experiment.
Well, actually the fairest test is to use high-precision real-wattage recorder to measure home energy consumption with the device attached and with it removed. We all have one of these: the electric meter outside the house. Run your electric clothes dryer, hook up the "power saver" device, then count the rotations of the meter disk for exactly one minute. Then unplug the device and count them for another minute. Repeat a few times. Can you see any difference? If so, is it large enough to justify the purchase price of the device?
One "power saver" does actually work. These are the NASA "Nola" devices used to control induction motors (for example, refrigerator motor). They remain controversial because they're mostly used industrially, and the energy savings is probably too small for any homeowner to justify buying the expensive controller. If someone tries to sell you one, they're probably lying about the expected amount of energy savings.