GFCIs on MWBC

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Old 09-20-17, 12:51 PM
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GFCIs on MWBC

Hello,
Forgive me if this a repeat, but I'd like to be sure I know exactly what's going on. I am installing 2 bathroom fan/light fixtures directly over the tub in 2 adjacent bathrooms on the same circuit. These need to be protected, so I bought a 15A single pole 120V GE breaker to protect the circuit. When I went to the panel box, I have the black wire going to one 15A breaker (both bathrooms, master bedroom) and red wire going to a 2nd 15A circuit breaker below the first (living room) coming from the same cable. The white and ground go to the neutral bar. From my reading here, I know that this is a multi-wire branched circuit. Also from my reading, it looks like to properly protect the 2 bathrooms, I have two options:

1) Install a 2-pole 15A GFCI 240V breaker ($90, but easier)
2) Install 15A GFCI outlets on all outlets ($25-$40, but more involved)

Are these my only options? Aside from the $ and time involved, are there any differences between my 2 options?

If I go with 1)...my panel uses the 1/2" slim breakers. The 2 breakers on the MWBC are stacked, does it matter WHERE in the panel I put the bigger 2-pole GFCI breaker? I have a few empty spots.

If I go with 2) Do ALL outlets need to be converted to GFCI (including those in the living room) or do ONLY the outlets on the bathroom circuit need to be changed out? Is there any special wiring I need to adhere to?

Bonus-----> Interestingly, the OUTLETS in the bathroom aren't part of either the bedroom/bathroom circuit or the living room circuit. Is it standard for bathroom outlets to be on a different circuit than bathroom lights/fans in the same location?

Thanks!!
 
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Old 09-20-17, 01:06 PM
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Have you looked at adding the fans to the existing lighting circuit ? You could use a dead front gfi to protect the fans.
 
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Old 09-20-17, 06:08 PM
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Is it standard for bathroom outlets to be on a different circuit than bathroom lights/fans in the same location?
Yes. Depending on the age of the house code requires the receptacle(s) in a bathroom for be on a separate 20 amp circuit.

my panel uses the 1/2" slim breakers. The 2 breakers on the MWBC are stacked, does it matter WHERE in the panel I put the bigger 2-pole GFCI breaker? I have a few empty spots.
Yes. The breaker needs to sit on opposite legs in the panel. If it is a full size breaker (not slim) this will not be an issue.

Do ALL outlets need to be converted to GFCI (including those in the living room) or do ONLY the outlets on the bathroom circuit need to be changed out?
No. You need to find where the multi wire circuit splits and either install the GFCI there, or anyplace just before the new fan/lights come into play on the circuit. You could even get a GFCI/Switch combo and install it at the first switch box.
 
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Old 09-21-17, 06:01 AM
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Is there any special wiring I need to adhere to?
Yes. Where the circuit splits, the shared neutral needs to be connected to any other neutrals directly, with any pigtails needed.
For example, you cannot use receptacle side terminals to continue the neutral downstream.
Pigtailing the neutral at the split ensures the neutral path will not be broken if the device fails.
 
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Old 09-25-17, 08:10 AM
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Thanks everybody! This is what I did Tolyn:
No. You need to find where the multi wire circuit splits and either install the GFCI there, or anyplace just before the new fan/lights come into play on the circuit. You could even get a GFCI/Switch combo and install it at the first switch box.

The outlet that is right before the bathrooms was a half-hot switched. The switched half was controlled by the switch by my bed and had 14/3 wire. I wired the existing 14/2 cable to the line of the GCFI and just added another outlet next to the GFCI. The new outlet is switched the using the red hot from the 14/3. There's a white jumper for the neutral back to the GFCI. Of course, all grounds are grounded. I tested it and all seems good. The GFCI stays powered at all times. The outlet next to it is switched. There's one more outlet on the circuit in the hallway. When I test any outlet on the circuit with the GFCI tester, both bathrooms go out along with the outlets. I now have a double gang box, but that outlet is pretty hidden and I get to keep my pole lamp connected to the switch This was definitely the best option and cost only $17ish as opposed to the $80 for a 2-pole GFCI breaker at the panel.
 
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