There used to be a device...might have been called a "green plug" or something, that you plugged an appliance like an air conditioner or refrigerator, and by supposedly clipping the sine wave, you got the same performance at lower watts.

Now, I mostly heard that this was smoke and mirrors, and in fact may damage a motor. I would not use it. But I am now being asked to find such a device for the wall A/C in a hotel ( 240VAC, 20 amp units.)

My question is this: does anyone have a reference to a good technical article debunking the devices, or...???