Why don't downstream outlets work after replacing a GFCI outlet?

Question

I have a GFCI receptacle in the garage. There are two regular outlets in the garage as well that I believe are "downstream"/protected by this outlet as required by code. There is also another regular outlet on the circuit that is inside in the closet (on wall between closet and garage). I plugged a tester into one of the regular outlets in the garage and accidentally hit the button to throw a fault. GFCI outlet tripped and will not reset. At this point, the outlet in the house appears to still work but the ones in the garage do not.

In the box for the GFCI receptacle, there are 3 cables coming into the box. There is one coming from the top and two from the bottom. I tried replacing the GFCI receptacle and thought I took care to put the wires in the same location, but now nothing works! The inside outlet no longer works so now I'm trying to figure out the correct way to wire the GFCI outlet.

I have been looking for a wiring diagram for GFCI when there are 3 cables but haven't found any. Is one cable the from the service panel and the other two load cables with one going to the inside outlet and the other going to the next outlet in the garage? (I would think the panel cable would be the one coming in from the top of the outlet box). But that isn't how it was wired. Worse, now the inside outlet isn't working either!

This is how it was wired (and I believe is the way I wired the new GFCI receptacle)

Top cable:   black wire goes to GFCI Line (position 1)
             white wire goes to GFCI Line (position 2)

Bottom Right cable:  black wire goes to GFCI Line (position 2)
                    white wire goes to GFCI Load

Bottom Left cable:  black wire goes to GFCI GFCI Load
                    white wire goes to GFCI Line (position 1)

I'm really confused. Since the inside outlet initially continued to work, I would think that it would be first in circuit directly from service panel. Then its load wire would come into the GFCI outlet as its line cable and there would be one load cable to the next outlet and then that outlet would feed the last outlet on the circuit. So why the 3 cables?

Answer 1

First, identify LINE and LOAD on the device

It sounds like you got nailed by the positioning issue. There is no central authority who makes terminal positions exactly the same on every device. If you want an eye-opener on that, just try a 3-way switch, which are different even within the same brand/model! So position cannot be relied on; you must examine labeling and screw colors.

On a receptacle screw colors will designate hot vs neutral. (Silver=neutral=white). Labeling and the warning sticker will designate LINE vs LOAD.

You are also trying to throw all the wires on at once and go Voilà. Even I don't do that. Here's what I do.

Also, no "back stab" connections. This is where you jab a wire in a hole and the hole grabs it and holds it. There's a different type called a "screw-to-clamp" where the hole is directly behind the screw and you must tighten the screw to clamp it; those are fine but tighten very firmly, preferably use the mandatory torque screwdriver to spec.

If you are in the habit of cutting wire ends off, stop - length is too precious and we will be setting wires several times potentially.

This will require a fair bit of capping off wires and testing, and many trips back and forth to the breaker to shut the circuit off while changing wires. We certainly don't work "live".

Hook up LINE, part 1

First, you identify the supply cable (hot and neutral) and hook that up to LINE. Test that by hooking it to LINE and capping off everything else, then temporarily mounting it so you can push TEST and RESET without getting nailed by current. Plug a load into the socket, a lamp will do.

Power up the breaker. Then confirm that the lamp lights, and the TEST and RESET buttons work appropriately. If not, that cable was not supply, try another.

LINE, part 2

Now, look for any other cables you want on LINE (that is, that you don't want to provide GFCI protection to). Go ahead and hook those to LINE also. If your GFCI only has 2 screws and any number of backstabs, then use pigtails.

It goes without saying that you are attaching white to silver screws, and black to brass screws. Also, the LOAD terminals are unused at this point.

Now, power up the circuit and conform that the lamp, TEST and RESET still work, and that you're powering up the right (to be unprotected) outlets.

Feel free to put a GFCI tester in them; they shouldn't trip. (If they trip a GFCI somewhere else, then this entire part of the circuit is already on that GFCI, and this GFCI here is totally redundant. Get rid of it.)

LOAD

What remains is branch(es) you want GFCI protected. Hook up one cable to the LOAD terminals. (If you have multiple cables to protect, wait. Just one for now.)

Do the testing dance again. And also, go to the to-be-protected outlets and try a GFCI tester there.

• If the outlet is grounded, the GFCI tester should trip.
• If the outlet is not grounded, the GFCI tester should not trip.

If the test fails, you have a ground fault in the downline of the cable you just added. It might be a plugged in appliance, or it might be in the wiring itself, such as a neutral screw grounding out, or a crossed neutral or hot with another circuit. It is unlikely to be the wire itself. Work that problem until it is solved and the GFCI tests clean.

Then if you have any other cables to add to LOAD, unhook the LOAD cable now attached and add the next, and test it standalone. Once they all test out, you can either attach 2 via Screw-to-clamp (if equipped) or pigtail.