I was attempting to upgrade an old outlet to a GFCI outlet. There are only two wires one black and one white. There is no ground wire. However the receptacle tester read "correct wiring". Is it possible that the outlet is grounded in some other fashion?
Electrical – Is it possible that this GFCI receptacle is grounded without an equipment grounding conductor being connected
electricalgrounding-and-bonding
Related Solutions
You are correct that the red should be power to the light, except the other side of the switch should take off from the line in side of the GFCI, there is no requirement for lighting to be protected by GFCI, so do not connect to the load side. The GFCI tripped because there was a mismatch in the currents between power wire and the neutral wire attached to the GFCI.
This is based on my best guess based on the information you provided. To be certain, you should examine the wiring in the other switch box to ensure the black is unswitched power, white is neutral, and the red is connected to another wire leading to the light. The main uncertainty is how the other switch plays into this scenario, as there were not enough wires for a 3 way setup with power to an outlet as well.
Incidentally, I would suggest avoiding the push-in terminals if binding screw connections are available. Doing so is more work, but it provides a better more reliable connection, provided the binding screw is properly used.
There should be no problem doing what you want.
One set of conductors brings power from an upstream device or outlet, while the other takes power to a downstream device or outlet. The two black conductors are electrically bonded through the receptacle, as are the two white conductors. You'll notice that the bonding tab on the side of the receptacle is still in place, which means that the two receptacles are connected together.
Replacing with a similar receptacle
If you're simply replacing the existing receptacle, with an identical (or similar) receptacle of a different color. Simply connect the new receptacle exactly as the original is connected.
- Disconnect the power by switching off the breaker, or removing the fuse.
- Connect the bare grounding conductor to the green grounding screw terminal.
- Connect the two white conductors to the silver colored screw terminals (one per terminal).
- Connect the two black conductors to the brass colored screw terminals (one per terminal).
NOTE: When terminating conductors at a screw terminal, always wrap the conductor in a clockwise direction. This will cause the conductor to be pulled in tight, when the screw is tightened down.
Installing a new fancy device without screw terminals
I'm not sure what conductor combinations the supplied twist-on wire connectors are rated for, so I'm going to assume they're only rated for 2 #14 conductors (check the documentation). So before you start, you'll want to pick up a couple Ideal yellow twist-on wire connectors.
- Disconnect the power by switching off the breaker, or removing the fuse.
- Connect the bare grounding conductor from the circuit, to the green grounding conductor from the device using one of the supplied twist-on wire connectors.
- Connect all the white conductors using a yellow twist-on wire connector.
- Connect all the black conductors using a yellow twist-on wire connector.
Additional Information:
- If this was a ground-fault circuit interruption (GFCI) receptacle (which it is not), the procedure would be different.
- If this was a split receptacle (half switched, or both halves supplied by different circuits) (which it is not), the procedure would also be different.
Related Topic
- Electrical – When replacing non-grounding type receptacles is a GFCI receptacle required, or can any GFCI device be used
- Electrical – Protecting multiple outlets with one GFCI; is it possible with this wiring scheme
- Electrical – How to install a GFCI receptacle to replace an old non-GFCI receptacle in a switch controlled outlet
- Electrical – How to replace electrical outlets that have two wires under same screw
- Electrical – Diagnose 125v 20a receptacle voltage
- Electrical – Trying to add an outlet on other side of wall, 3 pairs of white/black wires and ground
- Electrical – Why is the load circuit on the GFCI outlet dead
- Electrical – How to an outlet with only 2 wires (hot and neutral) be grounded
Best Answer
When you say the receptacle tester read "correct wiring", I am assuming that the existing receptacle was a three prong (had a ground pin) and that the tester was also a three prong, something like this.
If that is the case, it is probably reading ground through the metal box and the armored cable.
Before plastic boxes and non-metallic cable that used a continuous run of a separate bare or green ground wire, there was a grounding system that used the metal strap of the receptacle or switch, firmly screwed to the metal box, firmly screwed to the armored cable with was also firmly screwed to the service panel and through that, to ground. In later years, a bare aluminum wire was also included with the hot and neutral which (I believe) was intended to be a bonding strip.
This system worked. Sort of. It assumed that the metal connections were direct and firm at each juncture. The weakest part was probably the strap of the receptacle, which often sat on plaster and never touched the box. No metal-to-metal connection, no ground (although the aluminum wire, if properly connected, would provide ground). The connectors holding the armored cable to the box were also sometimes loose, leading to poor connection and poor ground. I think it is still code compliant and may be fine if proper techniques are used to install it.