What position should the on-off switch be in to turn the humidifier on, round circle down for on or the dash down? Which is on and off?

The power switch on the back of the humidifier typically has the dash as 'on' (dash down) and the circle as 'off' (circle down). However, we have received and sent out a few units with the switch attached backward. This does not affect the unit functions but can be a bit confusing. The best way to tell is plug in your unit, flip the switch and see which side is 'on'/'off'. Then mark it so you will always know.