Multi-Wire Branch Circuit - Common Neutral

[wyliesdiesels]

The grounding electrode conductor does not have to be in conduit.

It does if its #8.

 

[dledinger]

Big fan of MWBCs where permissible, and especially in shop environments.

Not a fan, in any application, of lights and receptacles on the same branch circuit.

I never liked seeing “shared neutral”, just because it’s not a very good description of what the neutral is doing.

Anyway, glad to see you’re getting it done.

 

[u2slow]

When I feed a wall of outlets off a 3-wire circuit, I tend to alternate which leg I hook up, or do a quad box with an outlet on each. It ends up with better load balancing, and you have both circuits available for future expansion. You can also add in a 240V outlet anywhere along that run.

Big fan of MWBCs where permissible, and especially in shop environments.

Not a fan, in any application, of lights and receptacles on the same branch circuit.

 

[alfredeneuman]

The fact that every POCO uses multiwire circuits exclusively from the generating station to the customer's service, yet some people don't want use them for their branch circuits has never made much sense to me.

 

[slow]

The biggest reason I don't like MWBC's is the required double pole GFCI requirements for places like "garages" A GFCI receptacle is $16, a 2 pole GFCI breaker is $80 for a SQD QO panel. Around here a 250 foot roll of 12/3 NM-B is $58 and a roll of 12/3 is 112 from home depot, so you are not really saving any money on wire cost if running romex.

If it was not for GFCI and ACFI requirements, and especially if running in conduit where you do have a wire cost savings no reason not to use them, but those are my reasons to not use them.

 

[AntonLargiader]

Are GFCI breakers really required, rather than GFCI receps?

The biggest reason I don't like MWBC's is the required double pole GFCI requirements for places like "garages" A GFCI receptacle is $16, a 2 pole GFCI breaker is $80 for a SQD QO panel. Around here a 250 foot roll of 12/3 NM-B is $58 and a roll of 12/3 is 112 from home depot, so you are not really saving any money on wire cost if running romex.

If it was not for GFCI and ACFI requirements, and especially if running in conduit where you do have a wire cost savings no reason not to use them, but those are my reasons to not use them.

 

[exranger06]

Are GFCI breakers really required, rather than GFCI receps?

Only if you're going to install GFCI receptacles at EVERY location. You can't feed a bunch of regular receptacles from the load side of a GFCI using a shared neutral.

Unless you're only using the shared neutral for the home run back to the panel, and it splits off into 2 individual circuits with their own separate neutral wires.

 

[AntonLargiader]

Depends what you are trying to do, I guess. My MWBCs go somewhere and then split to two different things, I can GFCI at the split and protect the rest of that branch. But if you're trying to keep that shared neutral as you go from device to device, yeah, that won't work.

Only if you're going to install GFCI receptacles at EVERY location. You can't feed a bunch of regular receptacles from the load side of a GFCI using a shared neutral.

Unless you're only using the shared neutral for the home run back to the panel, and it splits off into 2 individual circuits with their own separate neutral wires.

 

[dledinger]

Yep - and this is the reason there are so few MWBCs today. They’re basically legislated into the history books.

 

[alfredeneuman]

Yep - and this is the reason there are so few MWBCs today. They’re basically legislated into the history books.

How so and for what reason?

 

[wyliesdiesels]

Yep - and this is the reason there are so few MWBCs today. They’re basically legislated into the history books.

What?

 

[dledinger]

Lol...all I’m saying is that the GFCI requirements had a major impact in the use of MWBCs. That’s the most commonly cited example of why they are difficult to use and avoided.

 

[Norcal]

Lol...all I’m saying is that the GFCI requirements had a major impact in the use of MWBCs. That’s the most commonly cited example of why they are difficult to use and avoided.

I would not say they are difficult to use, a bit more expensive now but not difficult.

 

[wyliesdiesels]

Not difficult at all.

 

[u2slow]

Lol...all I’m saying is that the GFCI requirements had a major impact in the use of MWBCs. That’s the most commonly cited example of why they are difficult to use and avoided.

Oh the irony.... maybe its the GFCIs that make things difficult and should be avoided

 

[dledinger]

Oh the irony.... maybe its the GFCIs that make things difficult and should be avoided

I would put AFCIs at the top of that list.

 

[alfredeneuman]

I would put AFCIs at the top of that list.

2 pole dual function (with both AFCI and GFCI protection) cost more than regular breakers but just have 1 extra wire to terminate; the wire from the breaker to the neutral bar, so there is minimal additional labor involved. They even ship the breaker's wire pre-stripped

 

[AntonLargiader]

2 pole dual function (with both AFCI and GFCI protection) cost more than regular breakers but just have 1 extra wire to terminate; the wire from the breaker to the neutral bar, so there is minimal additional labor involved. They even ship the breaker's wire pre-stripped

Plug-on Neutral for the win.

 

[alfredeneuman]

Plug-on Neutral for the win.

 

[exranger06]

2 pole dual function (with both AFCI and GFCI protection) cost more than regular breakers but just have 1 extra wire to terminate; the wire from the breaker to the neutral bar, so there is minimal additional labor involved. They even ship the breaker's wire pre-stripped

I have Eaton CH panels in my house and Eaton doesn't make 2-pole dual function breakers; the only dual function breakers they offer are single pole.

 

[dledinger]

Anyway you decide to slice it, I’ve seen a huge decrease in the use of MWBCs. Maybe locale driven, I don’t know.

Regardless, I remain a fan particularly in shop applications.

 

[sberry]

I use them when it makes sense, need to reduce fill, long runs. Lots of places, small garages or simple residential I like it on single pole and simple.

 

[exranger06]

That one is AFCI only, no GFCI.

 

[alfredeneuman]

That one is AFCI only, no GFCI.

I realized that a bit too late, and deleted my post