Testing a GFCI Electrical Receptacle
Dear Mr. Electrician: I push the “Test” button on my bathroom GFCI (Ground fault circuit interrupter) receptacle occasionally, but nothing seems to happen. How do I know if the GFCI receptacle is working properly?
Answer: By pushing the “Test” button a simulated ground fault of approximately 6 milliamperes is shorted across the internal conductors and should cause the GFCI (Ground fault circuit interrupter) receptacle to stop working immediately. Normally you would hear a mild click sound and the “Reset” button might pop out a little. If the GFCI is not deactivated after pushing the “Test” button, the GFCI receptacle should be replaced as soon as possible because you are no longer protected against an electric shock or electrocution. Pushing in the “Reset” button should reactivate the GFCI receptacle. I have found that some “Reset” buttons need to be pushed in firmly using a blunt tool such as a screwdriver.
Another method that I also use to test a ground fault circuit interrupter receptacle is with my Ideal Voltage Tester. I put one prong from the voltage tester into the ground pin opening and the other prong into the neutral side of the receptacle which should always be the larger slot. That usually trips the GFCI if it is working properly. If it doesn’t trip, replacement is called for. Unfortunately the new tamper resistant receptacles prevent me from testing this way so I use my plug-in tester instead.
Replacing a GFCI Electrical Receptacle
To replace the ground fault interrupter receptacle you should begin by shutting off the power to that particular circuit at the main circuit breaker panel or main fuse panel. Test the receptacle with a lamp, radio, or an electrical tester to make sure that the GFCI receptacle is without power. This may not be totally effective as it is possible that a non-working GFCI receptacle may not have power available regardless. Therefore you should proceed to the next step with caution and test the actual wires at the screw terminals of the GFCI receptacle using a voltage tester, a voltmeter or a pigtail light socket with a lightbulb.
Remove the GFCI receptacle cover by unscrewing (Counterclockwise) the upper and lower screws on the cover plate. Next unscrew the upper and lower screws that secure the receptacle to the wall mounted electrical box. Carefully pull the GFCI receptacle straight out of the box as far as it will go. Take note of the wires connected to it. Look at the new Tamper Resistant GFCI Receptacle that you will be using to replace the old one. On the back you will see some words stamped into it. “Line” and “Load” are what you need to take notice of. Look at the back of the existing GFCI receptacle and take notice of which wires are on the “Line” and “Load” terminals.
Normally the wires are white and black. Black on the “Line” side would be the hot wire that feeds into the receptacle. The white wire on the “Line” side is the neutral conductor that provides a path for the return current from the black wire. Remove one wire from the existing receptacle and screw it onto the same terminal on the new GFCI receptacle. Repeat this for each wire until complete. By doing it this way you ensure to have the new GFCI receptacle wired the same as the old one. The green or bare wire gets connected under the green screw.
It is possible that the old GFCI receptacle did not have screw terminals for the connections, but instead had pigtails which were spliced to the wires in the electrical box using twist-on wire connectors. You can untwist the wire connectors by turning them counter-clockwise and separating the pigtail from each conductor in the box. Do this one at a time also and put the conductor on the same terminal as it was connected to on the old GFCI receptacle.
You may find that wires coming out of the electrical box are a little short to connect comfortably to the new GFCI receptacle. You should have a minimum of 3″ of wire extending past the edge of the electrical box. If the wires are too short you can splice short pieces of wire onto them. Use wires of the same gauge (Usually #14 or #12 solid or stranded). Strip the ends back approximately 1″ and hold the ends together so that they cross each other to form a narrow X. Using pliers twist the wires together tightly in a clockwise direction. Trim the end slightly with wire cutters so that you have 1/2″ to 3/4″ of bare twisted wire exposed. Use a medium size twist-on wire connectors to complete the splice. Twist the wire connector tightly by hand in a clockwise direction. Repeat this process for all of the short wires in the electrical box.
Begin the process of putting the new GFCI receptacle into the box by pushing the wires back into the box accordion style meaning that they are folded and bent in such a way as to compress back into the box as the GFCI is pushed in. Push the GFCI receptacle in enough to catch a few threads for each screw. Be sure that the GFCI is straight and flat. Take your screwdriver and push the GFCI support strap that holds the screw into the box at the lower point and the upper point. This will make it easier to turn the screws all the way down. Tighten the screws down but not snug. Check again to make sure that the GFCI is straight. If it isn’t, now is the time to tap the support strap gently with your screwdriver to the left or to the right to make it look level. There is room in the screw slot to allow for some alignment. After the GFCI receptacle is straight snug the mounting screws down and put the wall plate on. Push the “Reset” button and then push the “Test” button to make sure that the device is operating properly. Some GFCI receptacles are more difficult to reset than others. I sometimes have had to use a screwdriver and extra force in order to push the reset button in enough to reset. You can use a plug-in receptacle tester to check for proper polarity.
If you are replacing or installing a GFCI receptacle in a very old home, you may find my post on replacing two wire receptacles helpful.