If you've seen an Internet ad for capacitor-type power factor correction devices, you might be led to believe that using one can save you money on your residential electricity bill. However, a team including specialists at the National Institute of Standards and Technology (NIST) have recently explained* why the devices actually provide no savings by discussing the underlying physics. The devices—sometimes referred to as Amp Reduction Units or KVARs**—are touted as good investments because they reduce the amount of current drawn from power lines while simultaneously providing the necessary amount of current to appliances inside the house. Though engineers elsewhere...