If you look closely at a single-pole switch, you'll notice that the base of the toggle has some writing on it. One side says on and the other says off, if the switch is properly installed that is. Take a look at your switches to be sure that that's what they say. If you're unsure, let me give you a few clues to know if yours is incorrectly installed.
The first one is pretty obvious if you know what you're looking for. If the switch is flipped up and the light is on, the switch is properly installed. Up is on and down is off. The second giveaway is when the terminal connections of the switch are located on the right side of the switch. Most single-pole switches are designed this way now. But the easiest way to tell is when the switch pretty much tells you that you're an idiot! If you look at the switch and the writing says no, you know right away the switch is upside down.
Single pole switches are the only ones like this. Of course three-way switches and four-way switches are unmarked because, depending on their position relative to the other switch or switches, it could either be on or off. If you have a few switches upside down don't worry, it's not just a rookie mistake, even the professionals are guilty of this once in a while. The only difference is, you'd really have to twist their arm to get them to admit it.
