I have recently bought one of the cheap mains power meters (EL85-2042A to be precise) to monitor power consumption. It's really helpful when I need to know where my electricity bill comes from, or when I want to make sure I switched everything off before going out:
There's one thing I have noticed which I'm not sure how to explain. I have a few 12V LED spots powered via a transformer, and whenever I switch those on, the current on the meter goes down by 40 mA or so. A similar effect happens when I connect an old tranformer-based adapter powering an old clock radio.
As I understand this, most of my appliances ought to have capacitive kind of load, resulting in a leading power factor, so adding an inductive load with a lagging power factor compensates for that. What I would like to know is whether I will be really billed less when adding inductive load and consuming less reactive power, or do power companies take these effects into account and only bill for real power consumed?