GFI - Shared Neutral

[workin4living]

Hello everyone, I'm brand spankin new to this site and the field. I always seem to have questions so i'd like to begin with my first one! I tried searching these forums but didn't find exactly what I was looking for unless i missed it. Can you have a GFI share a neutral with another circuit that isn't a GFI?

 

[roger]

Can you have a GFI share a neutral with another circuit that isn't a GFI?

Yes, as long as it is on the load side of the GFCI device.

Roger

 

[workin4living]

Yes, as long as it is on the load side of the GFCI device.

Roger

Ok, so you're saying that as long as it's landed on the Load side of the GFI device ,correct? NOT if it's wired in upstream or down of the GFI. Sorry, I just want to make sure i'm understanding correctly. So if you have a 3 conductor ran and you use the Black for the GFI and then the Red goes on to another circuit then you can't share the neutral.

 

[workin4living]

Thank you!

 

[LarryFine]

To explain in more detail:

You can have a 3-wire circuit from the panel to the GFCI line terminals.

Each GFCI and its load wires must be wired as separate 2-wire circuits.

 

[gar]

080914-2026 EST

Roger, I do not understand the question and your answer.

In the original question I assume the referenced neutral to be shared is the neutral wire from the main panel to the GFCI device.

If so, then a circuit that is not protected by the GFCI can not be connected to the load side neutral terminal of the GFCI. If the not protected neutral was connected to the GFCI load side, then since the hot wire to this non-protected circuit bypasses the GFCI any load on the non-GFCI circuit would cause the GFCI to trip.

.

 

[480sparky]

I'm gonna really confuse the OP.......

You certainly can share a neutral. You just need to use a 2-pole GFI breaker.

 

[NolaTigaBait]

im confused... what 480soarky said about the 2 pole gfi breaker sounds like the simpleist way...is this the only way?

 

[480sparky]

im confused... what 480soarky said about the 2 pole gfi breaker sounds like the simpleist way...is this the only way?

Put it this way....

Can current (starting with the hot/ungrounded conductor) that flows through a GFI receptacle find it's way back to it's source without going back through the same GFI? If so, you can't do it that way because the GFI circuitry will sense an imbalance and trip.

You can share a neutral from the panel (MWBC) to a GFI receptacle, but from there you must break it down into two 2-wire circuits, one for each GFI device.

 

[NolaTigaBait]

ok, that makes sense

 

[NolaTigaBait]

thanks sparky

 

[ivsenroute]

I had this as a service call for a contractor who did his own wiring in a kitchen remodel that had a shared neutral and nothing would work from the GFCI on.

Since the cabinets were in and the tile backsplash was just put on the only way I could get the system to work was to put a GFCI receptacle in every open slot vs using one to protect regular duplex receptacles downstream off the load side of the GFCI.

The cost of the individual GFCIs makes the cost savings of the 12/3 wire not worth it.

 

[480sparky]

Pardon my crude drawings, but I think you'll get the idea.

(Neutral is shown in blue!)

With MWBC to first recep, going through two GFI line/load receps. Circuits are split into two 2-wire circuits:

Using MWBC and 2-pole GFI breaker:

If you tried to use a MWBC with 2 GFI receps, as soon as current flows through either or both circuits, an imbalance would be detected by the devices and would shut down.

 

[infinity]

080914-2026 EST

Roger, I do not understand the question and your answer.

In the original question I assume the referenced neutral to be shared is the neutral wire from the main panel to the GFCI device.

If so, then a circuit that is not protected by the GFCI can not be connected to the load side neutral terminal of the GFCI. If the not protected neutral was connected to the GFCI load side, then since the hot wire to this non-protected circuit bypasses the GFCI any load on the non-GFCI circuit would cause the GFCI to trip.

.

The problem with this original question and it's subsequent answers is that the OP failed to say whether or not this was a GFCI receptacle or circuit breaker. That little bit of information would have helped to limit the confusion.

 

[roger]

Gar, you are right, my answer was supposed to read "as long as it not on the load side...".

Roger

 

[yankj]

You can share the neutral, but ONLY on the LINE side of the GFI.