In electrical power systems using alternating current, the voltage and current can get out of step. This has the effect of reducing the real power in watts; to make up the shortfall the magnitude of the current must increase.

In this six-minute ‘kitchen tabletop talk‘, I try to explain the phenomenon and illustrate it with apparatus made from wire, a spring, string and a chopstick.

Poor power factor wastes energy mainly through excessive losses in transformers and distribution cables. So if you pay for electricity at high voltage and own your own transformers, it definitely pays to do something about poor power factor. But even if you don’t, your electricity supplier will claw back extra money from you through any invoice charges denominated in kVA (kilovolt amperes) or kVAh rather than kWh or kW.