Apparently pre-rinsing confuses the dishwasher or something. Not doing it leaves me with residue all over the other dishes though 🤷
It can be for anything you like. Dishwashers, dryers, heaters, hot water tanks, ac units, ovens, stoves, welders, car chargers, air compressors, hell, I've seen 220v coffee makers. If an appliance needs 220 it can be supplied.