old 2 wire romex

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steelersman

Senior Member
Location
Lake Ridge, VA
True.

Don't try putting a GFCI breaker on knob & tube. Most of the "circuits" have many taps. If they ran a hot wire and the already was a neutral close by they would just tap off the neutral
somewhere on this forum before I made a coment that you can't use a gfi on a circuit with a shared neutral (I remember one of my bosses telling me that a long time ago) and someone here said that you can and that there's nothing wrong with that. So now I wish I could remember who it was that said that and blast them!!
 

JohnJ0906

Senior Member
Location
Baltimore, MD
somewhere on this forum before I made a coment that you can't use a gfi on a circuit with a shared neutral (I remember one of my bosses telling me that a long time ago) and someone here said that you can and that there's nothing wrong with that. So now I wish I could remember who it was that said that and blast them!!

You can use 2-pole gfci breakers with a MWBC.
 

steelersman

Senior Member
Location
Lake Ridge, VA
You can use 2-pole gfci breakers with a MWBC.
I'm talking about putting a gfi recep. on first outlet of just one circuit where it's a 3 wire homerun, protecting the rest of the outlets downstream on the one circuit, and a pigtailing the neutrals of course. The other circuit just leaves the outlet box with a 2 wire and goes where ever.
 

JohnJ0906

Senior Member
Location
Baltimore, MD
I'm talking about putting a gfi recep. on first outlet of just one circuit where it's a 3 wire homerun, protecting the rest of the outlets downstream on the one circuit, and a pigtailing the neutrals of course. The other circuit just leaves the outlet box with a 2 wire and goes where ever.

As long as the load neutral is kept separate, this should work fine.

You would pigtail the MWBC neutral and the 2nd circuit neutral, with the pigtail being the line neutral of the GFCI.

You can't share neutrals on the load side of a GFCI receptacle, or 1-pole GFCI breaker.
 

steelersman

Senior Member
Location
Lake Ridge, VA
As long as the load neutral is kept separate, this should work fine.

You would pigtail the MWBC neutral and the 2nd circuit neutral, with the pigtail being the line neutral of the GFCI.

You can't share neutrals on the load side of a GFCI receptacle, or 1-pole GFCI breaker.
I always thought this was ok to do until along time ago my boss said that it won't work. I had run a 14-3 homerun to a gfi outlet in the ufinished part of a basement for the outside and garage outlets. Then the other circuit was tied through to a sump pump outlet if I remember correctly. And I wired it just like you said.
 

quogueelectric

Senior Member
Location
new york
yeah I'm going to install a gfci breaker cause the homebuyer is paying for it (otherwise I'd just get one gfci receptacle). How about the 2 wire romex without a ground? You guys ever seen it?
It is very common in older homes by me. Put a gfci breaker in and run around with those little stickers and put them on the outlets that are protected.
 

LarryFine

Master Electrician Electric Contractor Richmond VA
Location
Henrico County, VA
Occupation
Electrical Contractor
I always thought this was ok to do until along time ago my boss said that it won't work. I had run a 14-3 homerun to a gfi outlet in the ufinished part of a basement for the outside and garage outlets. Then the other circuit was tied through to a sump pump outlet if I remember correctly. And I wired it just like you said.
As long as you divide the 3-wire circuit into two 2-wire circuits before hitting the GFCI receptacle(s), and only land the conductors of one 2-wire circuit on each one, it should work.
 

steelersman

Senior Member
Location
Lake Ridge, VA
As long as you divide the 3-wire circuit into two 2-wire circuits before hitting the GFCI receptacle(s), and only land the conductors of one 2-wire circuit on each one, it should work.
will it still work if you put the gfi at the homerun outlet and pigtail the neutral from the homerun with the neutral circuit #2 (the circuit that does not need any gfi protection) and land that on the line side of the gfi and on the load side of the gfi you have the 2 wire connected which goes downstream and supplies the rest of circuit #1 (the one that you do want gfi protection for)? This should work correct?
 

76nemo

Senior Member
Location
Ogdensburg, NY
Sure it will work, but think about about it. Piggying off the line side wouldn't pass current through the CT, so you have NO GFCI protection. You're not saying ungrounded load side, grounded line side right?
 

JohnJ0906

Senior Member
Location
Baltimore, MD
I'm talking about putting a gfi recep. on first outlet of just one circuit where it's a 3 wire homerun, protecting the rest of the outlets downstream on the one circuit, and a pigtailing the neutrals of course. The other circuit just leaves the outlet box with a 2 wire and goes where ever.

Is this what we are talking about?

MWBC-GFCI.jpg
 
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