Teardown and test of a home power saving plug.04:33

These “power saving” plugs are widely available on the Internet. The premise is that you plug them into ANY socket in your home and suddenly your electricity bill gets lower. These claims are usually backed up by testimonials from satisfied users who quote staggering savings on their electricity bills.
In reality the plugs have no significant effect on a home power bill, since the only effect they have is random compensation for any continuous inductive loads in the home like transformers in power supplies. But even then, it’s just a random correction of power factor (relationship of the voltage waveform to the current waveform) and as this is not even monitored by most household meters it won’t have any effect on your bills at all.
What’s really notable about this particular unit is that it at least attempts to do something. Others I’ve looked at had the capacitor, but had one lead cut off it, rendering it useless! They also had bodged circuitry to light the LEDs. In this unit there’s a fuse for safety, an active 5uF capacitor, small VDR/MOV for transient suppression and a modest bit of circuitry to drive the LEDs on the front. It still won’t have any effect on your electricity bill, but at least it looks the part.