12/3 on the same phase

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michalspike

Senior Member
Some one run 12\3 to feed two different 120V circuit. We Arc-Fault this to splice red to Black wire and come out with one wire to a Arc-fault breaker.
If this is permit by electrical code?
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
Some one run 12\3 to feed two different 120V circuit. We Arc-Fault this to splice red to Black wire and come out with one wire to a Arc-fault breaker.
If this is permit by electrical code?


You could use a dp afci breaker but if you joined the black and red you know have one circuit. That could be compliant depending on what it feeds. If this is the two kitchen circuits then it may be an issue. What loads are on the circuits
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
we had inspection and we got objection because 12\3 on the same phase?
is there any code says you can't do that?
Basically what you did was make a 2 circuit run a single circuit. You could not land both legs on the same phase but if you tie them together then you have made it one circuit so you do not have a multiwire branch circuit anymore. The inspector is not seeing it that way so you will have to explain it to him. If you buy a dp afci then you can use it as 2 circuits but if one is enough for the load he should accept it.
 

michalspike

Senior Member
he was a really mean person. he didn't say a word after walk-thru apartment. we ask him if we pass or not he just say i will post it on the website. and even wrote there was no access to the roof to see ac unit there, and a leather to a roof was inside owners bedroom and we show him that. first time dealing with that kind of person.
 

electricalist

Senior Member
Location
dallas tx
Even though what you did was compliant There are some inspectors that my come acroos as "mean" when they understand this is a mwbc and that for some reason it wasnt put on a 2 pole afci breaker,,,,in short sometimes the reason for why we did something can be the reason why an inspectiom goes good or bad..
The first walk i do with an inspector i talk about the next time i will see him and go over my method...
 

Little Bill

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Staff member
Location
Tennessee NEC:2017
Occupation
Semi-Retired Electrician
Basically what you did was make a 2 circuit run a single circuit. You could not land both legs on the same phase but if you tie them together then you have made it one circuit so you do not have a multiwire branch circuit anymore. The inspector is not seeing it that way so you will have to explain it to him. If you buy a dp afci then you can use it as 2 circuits but if one is enough for the load he should accept it.

If they were on the same phase it wasn't a MWBC to start with.
I'm not sure why the OP did this but if he did it to save on adding another AFCI that might be why he was rejected.

Where I'm at we only have to put bedrooms on AFCI. Some were putting all the bedrooms on one or two circuits to cut down on costs of the AFCI. So now the state has an amendment that only allows so many outlets on each AFCI circuit. For example, we can only have 10 outlets on an AFCI protected circuit. So depending on the number of outlets in a room, you pretty much use all the allowed outlets in one room.
That might be what the OP's inspector was looking at.
 

kwired

Electron manager
Location
NE Nebraska
Sounds to me like we have a need to contact someone further up the chain of command - especially if you failed the inspection.

Unless there is a reason this needs to remain as a MWBC there is no violation as has been described so far. If it does need to remain as a MWBC then whatever code section stating that reason should be what is cited on the correction/failure notice.

Only other thing that comes to mind depending on exactly what was done is there is a chance of an improper parallel conductor situation - but if so that should also be mentioned on any report.
 

mwm1752

Senior Member
Location
Aspen, Colo
general lighting circuit have no quanity limits on recepticles even though it is a common & sensible practice. I agree with the group as long as you did not attach to more than 1 breaker it is not considered a multiconductor circuit. Unfortunately, some inspectors try to predict the future of what will be instead of realizing that they can only inspect what is physically done. For instance, after inspection it most likely would not be difficult to eliminate the AFCI & make 2 non afci circuits. His best approach is to note the specifics & move on IMO.
 

michalspike

Senior Member
i think he was just a badass. he didn't say a word at the time of the inspection. Even when he was leaving he just disappeared without anything. We have to chase him to ask what is the verdict. He just said i will post it.(nothing else). And he wrote: no access to roof to check AC unit, and we showed him where is the access to the roof(lather from bedroom site ). I guess he didn't want to go and have to find something. I already get two pole Afci breaker to change it. i don't want to argue with him if he will come back.
Thank You all for your help and wish you only smart inspectors.
 

GoldDigger

Moderator
Staff member
Location
Placerville, CA, USA
Occupation
Retired PV System Designer
To sum it up:
The original MWBC used a shared neutral, which was legal because the maximum neutral current would be no more than the current on one hot wire.
Putting black and red on separate breakers on the same phase would therefore be a violation.
But tying both to one breaker (splicing rather than double lugging) is just fine.
I could see some concern about the color identification, but not rising to a code violation.
As noted earlier, it really comes down to whether load calculations or circuit a specific rules required two circuits in the first place.
 

kwired

Electron manager
Location
NE Nebraska
were both on the same breaker? If so maybe he had problem with 2 wires under same lug?

We can come up with many possibilities such as that which could be reason for failing inspection but if one of those many possibilities is the issue - why doesn't the inspector specify exactly what the problem is instead of a non specific problem of two conductors on same phase:(
 

Sierrasparky

Senior Member
Location
USA
Occupation
Electrician ,contractor
What a arrogant you no what. Would not look ay the ladder access and then places a violation .



Is this online posting for the public to see or is it password protected.
If this is for the whole world to see , gee frikin wiz. :eek:hmy:
 

electricalist

Senior Member
Location
dallas tx
I'd say since the opportunity post said they went back and put a 2 afci on it that the inspector may have seen that the original fix wasn't right.
Stating someone ran a 12-3 doesn't tell if this was new construction or a remodel. If it was new and there was room in the panel. Inspect might think you guys weren't for the final. Red tag good bye. Maybe
 
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