In the age of mechanical electric meters, there is an urban legend that there are “lucky” electrical appliances. Once plugged in, the electric meter will go backwards. It may originate from the interaction between the strong capacitive load and the inductance of the coil in the meter, but for ordinary home users, it is still largely fabricated. This is not to say that the meters cannot be fooled to do weird things, as a team at the University of Twente proved by sending some more modern meters to run backwards. How did they create this miracle? Electromagnetic interference of dimmer switch.
read paper (PDF link) Obviously, this behavior is the result of the dimmer switch being able to shift the phase of the current pulse relative to the voltage cycle. AC dimmers are obsolete in 2021, but for those unfamiliar with their operation, they work by turning on themselves only during a part of the main power cycle. The cycle time is changed by dimming control. Therefore, the time between the zero-crossing point of the mains and its conduction point is equivalent to the phase shift of the current waveform. Since electric meters rely heavily on this phase relationship, their performance can be adjusted. Maybe the European store will now be ready for the operation of the dimmer switch.
If you are curious about these old-fashioned dimmers, please check out some of their basic functions.
thanks [Dorus] tip.