How To Test an Electrical Outlet for Ground
The wiring in your home consists of the "line" or "hot" wire, the neutral wire and in for at least the past couple decades, a ground wire. In the United States the common color coding for these wires are black or red for the hot wire, white for the neutral wire and green or bare wire for the ground wire.
To test whether an outlet is properly grounded, you will need an inexpensive tool called a circuit tester (you can also use a multimeter set to AC voltage appropriate for the outlet you are testing). Standard outlets have a large slot, a small slot and a "U" shaped hole. In a properly wired outlet, the smaller slot is "hot", the large slot is neutral and the "U" shaped hole is ground.
Insert one probe of the circuit tester into the small slot and the other probe into the large probe. If the circuit tester lights up, you have power to the outlet. Now place one probe in the small slot and the other probe into the "U" shaped ground hole. The indicator should light up if the outlet is grounded. Test both outlets because they can be wired separately. The fact that one is properly wired does not guarantee that they are both properly wired.
If the tester does not light, then place one probe into the large slot and the other probe in the ground hole. If it does light, then the outlet is grounded but the "hot" and neutral wires are reversed. If it still does not light, then the outlet is NOT grounded. If the outlet is miswired or not grounded, it should NOT be used until the problem is corrected.