Outlets that seem to be on same circuit, but not behaving that way

gfcireceptacle

I'm trying to install a GFCI outlet in my kitchen. My understanding is that you can install one GFCI on the circuit and this will protect all of the other outlets. This is assuming that the GFCI outlet is installed at the beginning of the circuit. (Correct me if I'm wrong about this).

In attempting to identify the outlet at the start of the circuit, I went one by one and disconnected each one of them, testing the others as I did that. They all seem to operate independently of each other. Disconnecting one outlet did nothing to the others.

What makes this puzzling to me is they are all connected to the same circuit breaker. So wouldn't this mean they are all on the same circuit? If they are all on the same circuit, why do all of them continue to work no matter which one is disconnected?

Best Answer

The old way of running kitchen plugs was to split the top and bottom plugs so each plug was on a seperate feed. This was accomplished by running 3 wire between the plugs and removing the breaker tabs, the entire thing was conected to a dual pole break so the entire plug would trip at once.

If your house was built to code before the advent of gfci this is probably what is going on.

If you test the breakers for those plugs and find them tied together with breaker bars or some othe way this is almost certainly the case.

Unless they were wired with 12g cable you will need dual pole 15a gfci breakers rather than 20a gfci plugs to add gfci protection or to run new cable and 20a breakers.

Fyi: not an electrician

Resetting the GFCI

If the GFCI has tripped, it can usually be reset simply by pressing the RESET button. If you press the RESET button and don't feel/hear a click and/or the button doesn't stay in, it means there is a problem and the internal mechanism is not allowing the GFCI to be reset. You can try pressing the TEST button, then pressing the RESET button again making sure you press the RESET button all the way in. If the device still will not reset, you'll have to try and determine the reason.

Why won't a GFCI device reset?

There are three reasons a GFCI device will not reset.

Wiring is wrong

If the GFCI device is not wired properly (LINE and LOAD reversed, hot and neutral reversed, etc.), the device will not allow a reset.

There is a ground-fault

Obviously, if there is a ground fault, the device will trip as soon as you try to reset it.

There is a problem with the device

If the device has gone bad, it will (should) not reset. Some devices will continue to hold, even if there is something wrong internally. However once they trip, they cannot be reset. Other devices will trip as soon as something internal dies, and will not reset. This is why monthly testing is suggested. If you press the TEST button, and then are unable to reset the device. You'll be made aware of a problem sooner, and can have it repaired (hopefully) before any damage is done.

Rewiring a new device

Before you begin, turn off the power at the fuse/breaker box and make sure it's off.

Locate the supply wire pair

There should be an ungrounded (hot) and grounded (neutral) conductor pair (likely as part of a cable assembly), that supplies power to the circuit. As it sounds like you've already located these, I won't go into detail as to how to locate them here (there are many other answers on the site that explain this procedure).

Terminate the supply wire pair

Connect the bare/green grounding conductor to the green grounding screw on the receptacle (and to the box if required), and to any other bare/green grounding conductors.
Connect the (white) grounded (neutral) conductor to the silver colored screw terminal labeled LINE on the device.
Connect the (black) ungrounded (hot) conductor to the brass colored screw terminal labeled LINE on the device.

Terminate load side wires

If there are devices downstream that require GFCI protection, you'll have to connect the wires feeding those devices to the LOAD side terminals on the device.

Connect the bare/green grounding conductor to the grounding conductors in the box.
Connect the (white) grounded (neutral) conductor to the silver screw terminal labeled LOAD on the device.
Connect the (black) ungrounded (hot) conductor to the brass screw terminal labeled LOAD on the device.

Set the device

Once all the wires are connected, install the device in the box using the mounting screws. Install the face plate, and turn the power back on.

Press the RESET button.
- You should have power to both receptacles, and any downstream devices.
Press the TEST button.
- You should no longer have power at the receptacles, or any downstream devices.
Press the RESET button again.
- Power should be restored to the receptacles, and downstream devices.

Installing GFCI outlets in multiwire branch circuit

This type of shared-neutral wiring is called a Multi-wire Branch Circuit, or MWBC.

All these issues are entirely mooted in your case, since you will not be able to use the LOAD terminals at all. There's simply no way to do it. You only have two receptacle sites per MWBC. The whole point of an MWBC is to make good use of both hot legs. Well, you need two GFCI+receptacle devices to do that. And that fills both sites. So the issue of extending off the LOAD terminals of one of the GFCI+receptacles will never come up.

A GFCI that doesn't use its LOAD terminals can't have a shared neutral problem.

Scenario 1:

As you propose, in box 1 of each circuit, connect the GFCI+Receptacle device to the LINE terminals only. Connect black and neutral, and cap red. In box 2, cap the black and comnect red and neutral to the LINE terminals. And you are done. There is no use for the LOAD terminals, leave the tape on them.

Before, the 8 sockets went to circuits as follows: 1.2------1.2------3.4------3.4

Now, the 8 sockets go to circuits as follows: 1:1------2:2-------3:3------4:4

Keep that in mind when plugging in heavy draw appliances. I.e, it's no longer "pick one socket, 1 on top 1 on bottom", now it's "1 appliance per GFCI". If you liked the other way, see Scenario 2.

Now, if you need AFCI protection, you need the newer cAFCI breakers designed to work in MWBCs, that do not need the circuit's neutral wire landed on the breaker. (the AFCI may have its own neutral pigtail, this is only to power itself.) These are all 1-pole breakers, so you will need a listed handle-tie to tie them together so they are shut off together for maintenance. This will resemble a 2-pole breaker.

Scenario 2

This depends on not needing AFCI.

In this case, you leave the wiring exactly as you found it. You will then replace those 2-pole or handle-tied breakers with 2-pole GFCI breakers. In this you land all 3 wires (2 hots+neutral) on the GFCI breaker. You cannot handle-tie two singles because of the shared neutral.

If you can find a 2-pole cAFCI+GFCI+breaker device, you can use that. I haven't been able to find one.

As far as the answers you're not understanding, Tester101‘s postings are sublime, among the finest on the forum. There's a lot of technical data there, and the volume of material makes it confusing when these concepts are new. I see no conflict nor contradiction in what he wrote.

About neutral sharing, he means in the context of MWBC and protecting downline loads using the LOAD terminals. You cannot. The one neutral can't be both the Load side of the black subcircuit and the line side of the red subcircuit. Thus, GFCI receptacles on MWBCs cannot protect downline loads, their LOAD terminals are useless.