Multi wire branch circuits in So Cal

David M

Member
Location
San Diego
I am currently "on loan" to a local So Cal C-10 as my regular company is slow right now and the two owners are friends. I myself have a had a C-10 since 1982 and am a state certified journeyman as well but frankly I don't do that much electrical anymore, this is a temporary position. Anyway the "boss" is telling me that multiwire branch circuits are no longer allowed and he has us pulling a separate neutral for every circuit. This HAS to be BS, no? He only buys 12/2 when metal clad is called for, says the common neutral stuff is no longer code compliant. Please tell me he's an idiot, this can't be true can it? I'll admit I'm a bit out of date on the NEC and there could be some local jurisdiction thing going on but still it just seems totally implausible to me. I understand the tie bar on the breakers but separate neutrals???????? Seems like NEMA would have stopped that in it's tracks, no more 3 or 4 wire products? Oh just to be clear the application is light commercial, in this case a fast food restaurant. Comments?
 

GoldDigger

Moderator
Staff member
A lot of commercial is no MWBC by spec now.
But that is just customer spec, not NEC.

NEC has added requirements for handle tie or common trip and it also makes some GFCI/AFCI circuits harder to troubleshoot. Based on those hassles some contractors may elect not run MWBCs any more. But I think that is a mistake.
 

charlie b

Moderator
Staff member
Location
Seattle, WA
Occupation
Electrical Engineer
I have a PE license in CA, and have done several projects recently in that state. I have not encountered any state or local code that explicitly forbids MWBCs. Indeed, I have included them in some of my recent CA projects.

So let me suggest that you invoke "Charlie's Rule" on your boss. Ask him to show you, in writing, where the code says no MWBCs in CA.
 

David M

Member
Location
San Diego

So let me suggest that you invoke "Charlie's Rule" on your boss. Ask him to show you, in writing, where the code says no MWBCs in CA.
:) I have invoked that rule so many times times in the past 43 years I have learned to use it very carefully, some people just don't don't shine to being made to look like idiots. Especially when they either sign your checks or happen to be "the authority having jurisdiction". Don't get me started on the FMC/ LFMC "six foot rule" that every electrician knows :D
 

Fulthrotl

~~Please excuse the mess. Sig under construction~~
I understand the tie bar on the breakers but separate neutrals???????? Seems like NEMA would have stopped that in it's tracks, no more 3 or 4 wire products? Oh just to be clear the application is light commercial, in this case a fast food restaurant. Comments?
in the ABSENCE of the tied breaker, you need separate neutrals.
otherwise, MWBC practices are permitted, with the appropriate tie.

it's ok, once you dodge this bullet, we have a new bullet for you.

Title 24:2016 Lighting Compliance. don't forget your third party certificate.
just when you thought it was safe not to jump off the roof.

welcome to california. remember to duck.
 

oddjobfix

Member
Location
Long Beach CA
Have you priced a dbl pole AFCI breaker lately? In the end, a little more wire and the cost difference in the breakers will come out better not using MWBC's. New code allows more than one feed to a detached garage which does not need AAFCI protection. You can now use a MWBC there. So to answer your question, you can still use a MWBC in some areas.
However, note that all lighting circuits need a neutral at every switch. Just sayin'. I'd go with what the boss wants.
 

Beaches EE

Senior Member
Location
NE Florida
Occupation
Electrical Engineer / Facilities Manager
While it is mainly a design and/or specification decision, once the breaker / cable costs wash out the advantage of a single circuit in the future is simplified troubleshooting. At the end of the day, there are good and not so good applications for MWBCs.
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Electrical Contractor
Have you priced a dbl pole AFCI breaker lately? In the end, a little more wire and the cost difference in the breakers will come out better not using MWBC's. New code allows more than one feed to a detached garage which does not need AAFCI protection. You can now use a MWBC there. So to answer your question, you can still use a MWBC in some areas.
However, note that all lighting circuits need a neutral at every switch. Just sayin'. I'd go with what the boss wants.
I think the op is talking about commercial work. If so no afci is required
 

Beaches EE

Senior Member
Location
NE Florida
Occupation
Electrical Engineer / Facilities Manager
Yes, you are right Dennis. I was making a more general statement and should have been specific.
 

roger

Moderator
Staff member
Location
Fl
Occupation
Electrician
While it is mainly a design and/or specification decision, once the breaker / cable costs wash out the advantage of a single circuit in the future is simplified troubleshooting. At the end of the day, there are good and not so good applications for MWBCs.
Don't forget there will be continuous savings in reduced wattage losses, material costs are just a part of the advantages.

Roger
 

charlie b

Moderator
Staff member
Location
Seattle, WA
Occupation
Electrical Engineer
Why are we posting into a three year old thread? I thought threads were automatically closed after being idle for one year.
 

roger

Moderator
Staff member
Location
Fl
Occupation
Electrician
I have been closing them as they are resurected but this one struck a nerve. 😉

Roger
 
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