It's not clear why your outlets might be upside-down, as the electrical code mandates nothing regarding positioning. My best guess is that your outlet is controlled by a switch. So, you might have a light switch turning the outlet on and off, which is valuable when you have a floor lamp you want to turn on when you enter a room. Some electricians will turn the outlet upside-down to indicate a switch-controlled receptacle.
Barring that, it could be:
- The electrician simply put the outlets in upside-down because that is his convention.
- It may be seen as being safer. If a three-prong ground plug of this type comes partially out, a metallic object that accidentally hits it will hit the ground first.
- It holds better. Some electricians and DIYers may believe that a three-prong plug installed in this fashion holds tighter into the outlet.
- Go to your electrical service panel and off the circuit breaker.
- Turn out the screws holding the face place in place.
- Turn out the screws holding the outlet in place.
- Gently turn the outlet around 180 degrees so that it is now "right." Caution: be very careful when you turn the wires, so that you do not dislodge any connections.
- Replace outlet screws and face plate.