Multi wire branch circuit (MWBC) and GFCI


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Old 11-07-16, 04:38 PM
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Multi wire branch circuit (MWBC) and GFCI

MWBC. 20 amp GFCI double pole breaker. 12/3 wire. 10 standard outlets, alternating on the circuit.

Does only the first outlet need to have the whites pigtailed then attached to the outlet LINE?

Does ground returning to the box need to be grounded in the service panel?

On mine only the first whites are pigtailed and attached to LINE, all subsequent have each neutral attached to the outlet. The incoming ground is grounded inside the service panel.

When tested, volts read normal. Ground is indicated. GFCI test at each trips the breaker. Test button on breaker trips it.

Am I missing anything? Will people die if I leave it configured as described?

Thanks in advance.
 
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Old 11-07-16, 06:31 PM
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Just to make sure we are on the same page: You do not need GFCI receptacles since you have a GFCI breaker.

Does only the first outlet need to have the whites pigtailed then attached to the outlet LINE?
All receptacles should be pigtailed. Not because of the GFCI, but because it is a MWBC.

Does ground returning to the box need to be grounded in the service panel?
Yes, of course. Grounds are always terminated in the service panel.
 
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Old 11-07-16, 06:38 PM
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On mine only the first whites are pigtailed and attached to LINE, all subsequent have each neutral attached to the outlet.
In your case..... what's the difference between white and neutral ?
The white comes from the GFI breaker and connects to all the receptacles.

I'm trying to figure out what line is and neutral.
Did you run two white wires ?
 
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Old 11-08-16, 03:32 AM
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Tolyn Ironhand - All outlets are standard. Only the breaker is GFCI.

Pjmax - Sorry, I interchangeably used the words white/neutral, they are the same. On outlets two through 10 I attached line neutral to one of the silver screws and load neutral to the other silver screw. I'm getting varying responses/opinions as to whether outlet two through ten neutral should be pigtailed to just one of the silver screws.

Thank you.
 
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Old 11-08-16, 07:34 AM
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They should be pigtailed with a wirenut connection. On an MWBC the neutral must maintain connectivity even if a device in the middle of the circuit is removed or damaged.
 
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Old 11-09-16, 04:09 AM
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Thank you. Project complete thanks to the folks participating in this forum.
 
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Old 11-09-16, 07:07 AM
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I'm getting varying responses/opinions as to whether outlet two through ten neutral should be pigtailed to just one of the silver screws.
Technically only the location where a MWBC splits requires the neutrals to be connected with a single pigtail to the receptacle. The downstream boxes are like two normal circuits.

I like to keep it simple and advise to pigtail all neutrals at every box if possible, you can't go wrong.
 
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Old 11-09-16, 07:26 AM
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If the incoming and continuing black wires are connected directly to each other (and/or the incoming and continuing red wires in a multiwire branch circuit are connected to each other) then the incoming and continuing white (neutral) wires must be connected directly to each other with pigtails used where applicable. This applies at any outlet box.

Do not use "both sets of terminals" (line and load) on a GFCI receptacle for the incoming and continuing wires of an MWBC. Pigtail it instead using the line terminals. The load terminals may only be continued with a 2 wire cable, which is treated as an independent subcircuit.
 
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Old 11-09-16, 09:32 AM
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Since 12-3 was used to connect the receptacles.... every receptacle is at a neutral split point and needs to be pigtailed.


I just finished repairing a kitchen in a small business. There was a 12-3 run from the panel to six receptacles. 12-3 between receptacles. No GFI's due to age. The wiring was spliced using all the receptacle screws and they were loose. What a mess with the melted receptacles..... not to mention what happened to the equipment that was lost when the neutral opened. Customer wanted to add GFI protection. Since the panel used bolt-in breakers I ended up installing six GFI receptacles with all wiring tailed.
 
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Old 11-09-16, 09:58 AM
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Since 12-3 was used to connect the receptacles.... every receptacle is at a neutral split point and needs to be pigtailed.
Not to beat a dead horse, but this is good info regarding the neutral and why it can't be broken.
If a beginner at wiring can understand this and connect the wires accordingly, you should be able to tackle almost any wiring job.
 
 

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