Old receptacle

While replacing some old receptacles I found this. The wiring is old and clearly whomever installed it was trying to trick someone from seeing it isn't grounded. This is the first in the circuit and I decided to replace it with a GFCI to protect the rest of them (ceiling fan/light, 6 recess lights, outdoor spotlight and two other outlets). The wiring to a GFCI outlet seems straight forward but when I turn the power back on, it keeps tripping. When I push the Reset button, it instantly trips again. All connected lights and outlets are turned off or not being used. Any advice?

  • Is the box grounded? Check for continuity from the box to the neutral (white) wires. It could be grounded if the feed is BX cable. (IIRC, that isn't acceptable for new construction.) – HABO Feb 1 at 22:27
  • Looks like the box is grounded, and everything else (minus the other outlet), are grounded as well. I daisy chained the wires to the GFCI and that did the trick, but it wont protect everything after it. – Andrew Golomb Feb 1 at 23:14
  • Can you post a photo looking squarely into the back of the box please? – ThreePhaseEel Feb 2 at 1:36
  • When you say the box is grounded is it from a bare copper conductor? If so the green wire jumper was added by a DIY person as an electrician would not have. I find bootleg grounds all the time. folks think since they are connected in the main panel it’s ok to connect them at other places it’s not. – Ed Beal Feb 2 at 23:23

The good news is that a properly installed GFCI effectively protects you not only from the ground faults that it is designed for, but also makes things so that the key use of the ground wire - to provide an alternate path for return current should there be certain types of failures in a device - will effectively be unnecessary because those same faults will also trip the GFCI. So safety-wise you'll be fine.

FYI, if you have a metal box, it may actually be grounded after all. You can test that by seeing if you get continuity between neutral and the bare metal box. If you do, then you can connect a ground wire to the GFCI receptacle ground screw and screw it into the box. And if the GFCI is "self grounding" then you won't even need that ground wire at all. But if you don't have that ground, you are still safe with a GFCI.

The key with a GFCI is to know which hot (black) and neutral (white) are LINE and which ones are LOAD. You have, as is typical, two hot wires and two white wires. One of those sets is coming from the breaker panel (line) and the other is feeding the next receptacle (load). If you know which is which, great. If you don't know:

non-contact tester

determine which black wire is actually hot. That is the LINE hot wire. The matching white wire is the load neutral wire. If you can't figure out which black & white wires are paired then it gets a little more complicated (but there are ways to figure it out).

Now that you have determined line vs. load:

  • Turn off the breaker
  • Connect the LINE wires only to the GFCI. The screws should be clearly labeled on the GFCI. (Hint: The LOAD screws are the ones that were originally covered with a piece of tape.)
  • Turn on the breaker
  • Test the GFCI - Test/Reset, plug in a device (lamp, radio, whatever) and Test again, etc.

If everything is good:

  • Turn off the breaker
  • Connect the LOAD wires to the other screws.
  • Turn on the breaker
  • Test the GFCI - everything should work now unless there is a wiring fault at one of the other receptacles.
  • Test the other receptacles.

"seems straightforward" except GFCIs wire completely differently from plain receps.

First, recognize the code violations here: a neutral-ground bootleg jumper, and b) 2 white wires on the same screw.

Here's how to hook up a GFCI recep.

Leave the "For Wizards Only" warning tape on the "Load" screws.

With power off... Take one of the cables - one you think is supply. Hook its black and white wires to the "Line" screws. Insulate all other wires because they could be hot. The side screws will also be hot, so temporarily mount it back in there well enough to push "Test" and "Reset". Also plug in a 2-prong appliance. Power back up and see if the GFCI will "test" and "reset" and if the appliance works.

If it doesn't, you selected the wrong cable. Do the last paragraph again with a different cable.

Now we've reached a checkpoint. The supply and GFCI are proven.

Now, attach any additional cables to the GFCI device. If you want the downline to have GFCI protection, use the "Load" terminals. Add one thing at a time.

If adding something causes the GFCI to trip, then there is a fault in whatever you added. Divide and conquer. Unplug all appliances and see if you can get the problem to clear. Divide the remaining circuit in half and see if that clears it. Etc.

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