Thre are a couple of different approaches described on those links. The first one simply reduces the voltage. So the lights run dimmer and use less electricity. That is OK if you can live with less light. But as they correctly show, there are batter ways (more efficient light fixtures).

The second link is talking about modifying, or fixing, the waveform to make motors run more efficiently. This is possible, but generally homes do not have predominately motor loads, with refrigeration being a major exception. So that approach would make sense for a factory with lots of big motors.

__________________
1998 C230 330,000 miles (currently dead of second failed EIS, yours will fail too, turning you into the dealer's personal human cash machine)
1988 F150 144,000 miles (leaks all the colors of the rainbow)
Previous stars: 1981 Brava 210,000 miles, 1978 128 150,000 miles, 1977 B200 Van 175,000 miles, 1972 Vega (great, if rusty, car), 1972 Celica, 1986.5 Supra