Do you you have a voltage tester?
I would start by making sure that the receptacle is polarized properly and grounded. If you have a tester, assuming that the receptacle is oriented so that the ground is at the bottom, test from the right side of the socket (the smaller slot) to ground. If it reads 120v, then the hot and neutral are polarized properly and the ground is intact.
If you get no reading, try the other slot. If you read 120v from the larger, left-hand slot, to ground the polarity is reversed and the power wiring needs to be exchanged on the back of the receptacle.
If neither slot reads a voltage to ground, then there is no ground wire hooked up to the receptacle.
I would start by making sure that the receptacle is polarized properly and grounded. If you have a tester, assuming that the receptacle is oriented so that the ground is at the bottom, test from the right side of the socket (the smaller slot) to ground. If it reads 120v, then the hot and neutral are polarized properly and the ground is intact.
If you get no reading, try the other slot. If you read 120v from the larger, left-hand slot, to ground the polarity is reversed and the power wiring needs to be exchanged on the back of the receptacle.
If neither slot reads a voltage to ground, then there is no ground wire hooked up to the receptacle.