Can I feed GFCI return though same conduit as feed?

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  #1  
Old 05-26-20, 05:04 PM
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Can I feed GFCI return though same conduit as feed?

I like to reuse a GFCI that is in a dedicated box for a newly added electrical box. That new box is wired thought an other box.

A.) New electrical box with outlet
B.) existing light switch box
C.) Existing box with GFCI

C is wired into B.
I like to wire A (passing through B) to C (using the GFCI out)

As a result there woudl be a hot phase from B to C conduit as well as the GFCI outpt phase.

Not sure if code permits this?

 
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Old 05-26-20, 06:22 PM
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That is fine as long as the conduit and any boxes are not overfilled per conductor fill calculations.
 
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Old 05-26-20, 06:48 PM
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Great. I am below standard fill for 14 AWG in 1/2" EMT.

I know there is Table 314.16(A). But not sure. how to count. I have two switches in there. 1 light toggle and one timer for fan. The box is connected as follows:
Current:
- in: phase and neutral
- out: feeding two outlets (each neutral and hot)
- out feeding light
- out: feeding fan
New:
- passthru hot


BTW. that is another reason that I prefer wire to route thought middle box that is already somewhat crowded with a fan timer.
 
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Old 05-26-20, 07:21 PM
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Each device counts as 2, all grounds as 1.
 
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Old 05-27-20, 05:06 AM
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If you have difficulty stuffing everything into the box then you need a bigger box regardless of the box fill count.

The ground fault circuit interrupter output phase needs its own neutral as well as its own hot. What comes off the load terminals of a GFCI receptalcle is to be treated as if it were an independent branch circuit, with none of its loads connected to neutrals that come from or went elsewhere.

So you would also have a pass through neutral from C (where the GFCI is) via B to A (new receptacle). No problem if you are within box count. You do not need a second ground wire between B and C. Different branch circuits in the same conduit may share the same ground wire sized for the largest of the circuits.

Hint: Before removing the yellow tape and hooking up anything to the GFCI receptacle load terminals, do a test power up and plug something into the receptacle and verify that everything works so far.

A pass through conductor counts as one provided it was not cut and having to be wire nutted back together in the box.
 

Last edited by AllanJ; 05-27-20 at 05:32 AM.
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Old 05-30-20, 12:07 PM
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I wired up as outlined - having an issue.

The GFCI trips as soon as I plug in any load to the new outlet. I used a wring tester plug, and all seems fine.
Just wondering.... I wired the hot from the GFCI load side to the new outlet. I did not wire a separate neutral from GFCI load to outlet. I thought the same neutral is shared. Is this an issue?
 
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Old 05-30-20, 12:42 PM
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I did not wire a separate neutral from GFCI load to outlet.
There is your problem. You must have LOAD neutral as well the LOAD hot.
 
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Old 05-30-20, 12:52 PM
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Thanks. At this point it will be easier for me to switch load wire over to line and wire a new GFCI at the new outlet location.
 
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Old 05-30-20, 01:55 PM
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No point in running load back. Just pick up the line wires at the other end. You could then put the existing LINE wires on the LOAD and feed current GFCI from THE LOAD.
 
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Old 05-30-20, 02:21 PM
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Regarding:
"You could then put the existing LINE wires on the LOAD and feed current GFCI from THE LOAD."
Not sure that I follow.

If I stuck to plan A, can I feed two neutrals in one conduit? One form load terminal to outlet and one neutral for girths and fan?
 
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Old 05-30-20, 03:44 PM
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Let me see if I can clarify it.
You have two boxes joined by conduit. Power comes into #1 Which is connected to #2 via conduit.
Your plan is to feed power into #1 and through to #2. Install a GFCI in #2 and run GFCI protected LOAD wires back to a receptacle in #1.
Why not install the GFCI in #1 and then feed a regular receptacle in #2 off the LOAD in #1. Both receptacles will be GFCI protected by #1.
 
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Old 05-30-20, 04:16 PM
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Yes you can have two unshared neutrals going through the same conduit. In fact if you have any two different branch circuits with 120 volts sharing a conduit they must have their own neutrals

Since you just added a passthrough hot from the existing GFCI (box C) to the new receptacle (box A) all you need is a passthrough separate neutral running the same path, space permitting.

... Why not install ... ?
Note: The existing GFCI will remain in the same place, box C.
 
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Old 05-30-20, 04:22 PM
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Let me try to illustrate. So far, I wired up from GFCI Load hot to new outlet. So I could feed a neutral from GFCI along side and use this as the neutral of the new outlet.

BTW. C gets line from B
The whole powder room (and some existing laundry) is fed though box B
 
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Last edited by destruct05; 05-30-20 at 04:39 PM.
  #14  
Old 05-30-20, 04:36 PM
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Oops, I thought box A was connected to box B with the light switch, not previously unmentioned box D with the light fixture. This changes the whole complexion of the thread.

OT follows:

While no harm is done wiring up box A in the previously unmentioned laundry room as described, full compliance with (U.S.) code requires a separate 12 gauge circuit from the panel t and serving just receptalcles in a laundry room only..

And full compliance with code requires the existence of a 20 amp circuit serving just things in one bathroom or serving just receptacles in one or more bathrooms.
 
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Old 05-30-20, 04:42 PM
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Yes, also is a powder room a bathroom complexity.
The laundry room has a dedicated 20 amp for the washer and dryer. Technically, since powder room is viewed a bathroom I have a bit a challenge. But the light of laundry room and one existing outlet is fed by powder room. Possibly was code 20 years ago. There is just no way for me to connect my new outlet to the 20amp laundry room outlet without major drywall work....
 
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Old 05-30-20, 04:53 PM
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If or when a 20 amp dedicated bathroom circuit is added, the 15 amp circuit the subject of this thread may remain as it stands then.
 
  #17  
Old 05-30-20, 05:27 PM
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The red LOAD line must be a hot AND a neutral from the GFCI or the GFCI will trip since it does not see the same current on the hot and neutral. That neutral has to be separate from the fan and light neutral.
 
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