I recently attempted to update a basic 3-prong outlet to a GFCI outlet (so that I could connect a do-it-yourself, low-voltage, exterior lighting kit to this outlet). It seemed to work for the most part, but I have three issues of concern.

1) The breaker for this circuit (and this outlet seems to be the only thing on this circuit) is a 20 amp breaker. Is it OK to use a 15 amp GFCI outlet? The old outlet is rated for 15A.

2) There were two cables coming into the outlet box. One had all three wires (white, black, bare) connected to the old outlet. The other had the white and black wires taped off, and the bare wire connected to the outlet's ground terminal along with the bare wire from the first cable. What could be the point of this? I attached the new outlet in the same manner.

3) My three-prong tester indicated that the new GFCI outlet was installed correctly, and when I pressed the test buttons (on the tester and the outlet itself) the circuit was tripped. However, when I plugged in the old lamp that was always connected to this outlet, there was a spark and the circuit tripped, and even left a small, black char on the outlet! When I connected a fax machine to the outlet as another test it seemed OK.

Two caveats: The plug on the lamp was wired by the previous home owner. Also, the old outlet indicated reversed hot/neutral when tested. There was never a problem using the lamp when it was connected to the old outlet.

That's a lot. Sorry to be so wordy. Thanks very much for any solutions.

My answers are in bold:


1) The breaker for this circuit (and this outlet seems to be the only thing on this circuit) is a 20 amp breaker. Is it OK to use a 15 amp GFCI outlet? The old outlet is rated for 15A.

Yes.

2) There were two cables coming into the outlet box. One had all three wires (white, black, bare) connected to the old outlet. The other had the white and black wires taped off, and the bare wire connected to the outlet's ground terminal along with the bare wire from the first cable. What could be the point of this? I attached the new outlet in the same manner.

Probably the taped wires were to an old outlet or some other device that has been removed or abandoned.


3) My three-prong tester indicated that the new GFCI outlet was installed correctly, and when I pressed the test buttons (on the tester and the outlet itself) the circuit was tripped. However, when I plugged in the old lamp that was always connected to this outlet, there was a spark and the circuit tripped, and even left a small, black char on the outlet! When I connected a fax machine to the outlet as another test it seemed OK.

If it tripped the GFI, then tester did what it is intended to. If it triped the breaker, we got to figure out why.

Seems there is a short (ground fault) in the lamp, it should be checked and repaired.


Two caveats: The plug on the lamp was wired by the previous home owner.

Is the lamp worth fixing?

Also, the old outlet indicated reversed hot/neutral when tested. There was never a problem using the lamp when it was connected to the old outlet.

Is the polarity correct now? Or is it still shows as reversed hot/neutral?