If you have a multimeter /voltmeter, turn it to AC Volts, 200V + range. In the US you should have a reading of 120V between hot and neutral, 120V between hot and ground, and 0V between neutral and ground. If you look at the outlet, you should see that there is a narrow prong, which is consider the "hot" prong, the wide prong is the "neutral" and the round prong is ground. Don't set your meter to current or you will ruin it. Check this [http://www.youtube.com/watch?v=bDhYDY9A4TI&feature=related|video] for the wiring of your outlet. This [http://www.youtube.com/watch?v=vfZAE1VQPEY&NR=1&feature=fvwp|video] will show you how to replace it. and always remember, '''SAFETY FIRST''' so you can measure it the way it is, BUT if you work on it....TURN THE POWER OFF.....If in doubt, get a licensed electrician to help you. Hope this helps a bit. Good Luck