I wired an addition for a residential remodel job. We ran two new 20-amp circuits from the main electrical panel to the new addition.

We used one 20-amp circuit for the north side of the addition and the other 20-amp circuit for the south side of the addition.

We ran a 12/3 romex cable from the main electrical panel to feed the addition.

I failed inspection. Inspector wants us to install a double pole 20-amp breaker for these circuits. His reasoning is that if you only turn off one circuit breaker. There is a potential danger because the neutral could still have a load on it.

Is this new? Is he right? I am going to comply. So we can pass inspection and get paid. I have never done this before. When one circuit overloads or short circuits, then both circuits will trip and kill power to the whole addition. This does not seem right to me.

Can any inspectors out there update me?

Thank You,

Tev

210.4(B) is a very misinterpreted code article, as your inspector has proven. I have never seen a multi-wire branch circuit with each phase on the same yoke (other than a 240 volt outlet), and doubt that I ever will. The only instance I could see this happening on is a switched receptacle where the electrician wants all the lights (including the switched potion of the receptacle) on one circuit, and all of the receptacles (including the unswitched portion) on another circuit, and he/she chooses to do it with a multi-wire branch circuit.

You are only required to use a two pole breaker where both legs land on a single device on one yoke strap such as a split wired receptacle. (Very common for a dishwasher and disposal circuit) If you ran the 12/3 to a junction box and than ran your two wire from there two single pole breakers will suffice. Be sure to put them on opposite phases.

Tev,

I agree with the others, it's not in the NEC.
I think I may have heard where it was a local Amendment somewhere, but am not sure.

BTW, I have heard of it being required in New Jersey, but don't know if that was an Inspector's preference or not.

Bill

Thanks for your posts,

I knew I was right. I called the inspector personally and asked specifically if he wants me to install a double pole breaker.

I wanted to talk to him to get a feel if he knew what he was talking about. Sometimes the inspectors have to inspect the plumbing, framing and electrical and they usually don't know to much about electrical.

I was suprised by him because he was talking about sharing a neutral and explaining how there could be a potential load on the neutral if both circuits are not turned off. So he sounded like he knew what he was talking about.

I don't like to tick these guys off. I just calmly explained that I didn't think it was right because if there is an overload or a short in one circuit, then both circuits would turn off and cut power off to the whole addition.

He still persisted in the double pole breaker so that is what I did. I can always go back and put the two single pole breakers on after we get the green tag. But I don't want to waste my time and money.

Just some of the obstacles us contractors have to go thru to get a job done.

Tev

Bill:
From the areas of NJ that I am familiar with, the context of this thread is NOT required.

Ocasionally, a mis-interpertation of the NEC is made, sometimes it's "I want"

Things are a changin......the "ol boys club" is becoming a thing of the past. The NEC is "the code" in all areas.

Two circuits (3 wire) to a single yoke (split recept) need a 2-pole cb. Two circuits, not accessable at a single yoke do not. I kind of follow the srgument that the "neutral" could be "hot", but you are supposed to pigtail your neutrals!!

John

In a "Perfect World" the inspector can not "make up" rules even if he thinks there is a good reason, to fail you he should provide the code article he feels you violated.

But in the "Real World" in the interest of speed and not getting this guy primmed for the next job he inspects for me, I would have done just what you did.


Bob

John,

A cousin-in-law had a dormer put up maybe 5 years ago in Tom's River and I went up to give him a hand. The inspector said the work looked great but wanted a tie-handle put on the breakers controlling multiwire circuits. I told him not to argue as it wasn't really a bad idea. I'm still on the fence with that.

Bill

Not part of the code but good practice to use tied breakers. My frend of 30 years had his son working with an electrician, he was in the attic working on a multiwire circuit, and they had one of the breakers off. He came in contact with the neutral and they lost him. Since then I use tied breaker on all multiwire circuits. That back feed can get the best of us. The inspectors in this area ask for 2 pole on multiwire.

Funny you should mention this...

I was just searching here not two weeks ago to see what the opinion was relative to 12/3 multiwire needing tied-in breakers.

Here were some of the results:
https://www.electrical-contractor.net/ubb/Forum2/HTML/000501.html

https://www.electrical-contractor.net/ubb/Forum2/HTML/000586.html

https://www.electrical-contractor.net/ubb/Forum1/HTML/000295.html

https://www.electrical-contractor.net/ubb/Forum1/HTML/001208.html

(Edit was to put carriage returns after each link. Wheeeee!)

[This message has been edited by ThinkGood (edited 09-16-2003).]

The handle ties would be a major problem in commercial work, many typical office cubes (modular office partitions) are designed to be fed multiwire (3 hots 1 Neutral).

It would basically put a whole section out when one person plugs in a heater for their feet.

LK I am sorry for your friend that lost someone, but I still do not agree with handle ties.

Would you also have the NEC say you can only have one circuit in a box?

As in two or more two wire circuits.

My views may be bias as I install and maintain multiwire circuits almost daily, and I do not see any more problems with these than 2 wire circuits.

It is difficult to actually get 208 or 240 volts when the neutral is lost, this would require a dead short on one side of the multiwire circuit and the loss of the neutral.(I will admit I have seen surge protectors taken out by lost neutrals)

It is not unusually for us to have an entire 42 circuit panel wired with multiwire circuits (42 hots 14 neutrals) as that is what the office furniture requires.

JMO, Bob

Bob,

You have a good point. Personally I don't see the same benefit to Handle Ties in Commercial work and wouldn't recommend that.

It does tick me a little to 'dumb down' things with a 2 pole breaker, but the fact is that many people that do Electrical work in homes are less than qualified to do so, and tie handles or common-trip breakers might help save someone.

I wouldn't oppose a code requirement for tie handles on multi-wire circuits in Residential occupancies.

JMO,
Bill

[This message has been edited by Bill Addiss (edited 09-16-2003).]

Why single this out? Why not leave wiring diagrams around the house for any intrepid homeowners looking to play Thomas Edison. Do you think the average handyman would know what an afci breaker is? What about a couple of threeways and fourways? A gfci breaker? Nevermind a multiwire circuit. Read the posts on the diy websites. A two pole breaker is not going to make one bit of difference. These nuts are flying blind and clearly don't have a clue. The fact is the NEC does not require this in the scenario above.

http://www.amazon.com/exec/obidos/ASIN/0584400101/ref=pd_ecc_rvi_1/103-1668485-5269451

As an ex-commercial electrician I think Bob nailed it on the head. I don't think a multi-wire branch circuit is any more dangerous than a two wire circuit...if worked on by qualified personnel. If I'm not mistaken, certian members of the IBEW have been trying to push a code into the NEC that would ban multiwire branch circuits altogether. The justification used is the danger in working on them.

Ryan,
Not only is there a danger working on a mulitwire bracnh circuit with only one hot locked out, it is also an OSHA violation. Part of the push for the common disconnect from the IBEW is beacause the OSHA hot work rules are being taught by the IBEW to their members and compliance with these rules would require that all of the hots for a multiwire branch circuit be locked out if you are working on the grounded conductor of that circuit. The use of common trip breakers or handle ties on the breakers feeding a multiwire branch circuit would make the OSHA required lockout of all of the hots on that circuit automatic.
Don

[This message has been edited by resqcapt19 (edited 09-17-2003).]

It is borderline insanity not to use an AC non-contact voltage tester when reworking any wiring, much less for a multiwire circuit. A critical part of qualified use is knowing when the tester may give "false positive" (like with “floating conductors” ) or "false negative?" (wet romex) indications.

Their use to check conductors after a neutral has been broken should be part of the routine, if there is any question of the circuit status.

Like has been mentioned earlier, noncontact AC testers are used daily on up to 765kV circuits.

Don, this is very disturbing to me.


So now we are saying IBEW trained (or otherwise trained) electricians need the protection to be automatic.

This is truly a sad state of affairs if electricians can not be properly trained.

Lets just install shunt trips on all circuits, activated by micro switches in every box, that when you take the cover of the box it would trip all associated breakers.

Bob

Bill:
Your solution is one that I use sometimes to expedite matters.

Guys, I remember a few times that someone got "bit" by an open neutral that was part of a multi-wire. They learned real fast!

Some of the cubicle jobs that we have done had a spec for 3 pole common trip cb's. I have to agree with Don about the OSHA reg, as that is the reasoning the architect/engineer wanted the 3 pole cb's. The heater problem was/is controlled by the office managers, as they have to answer to the bean counters "why" the electrician had to come in, and what was the cause. That's not the case at all sites, but it's becoming more prevelant. "Who's responsible"??

John

Bob,
I'm just saying that handle ties would let you use one lock in place of 2 or 3. These locks are required any time you are working on a grounded conductor of a multiwire branch circuit. If you are called in on a service call to work on a receptacle, how would you know if it is part of a multiwire branch circuit without doing a physical trace of the circuit? There is no code requirement that multiwire branch circuits and their grounded conductors be identifed as such. There isn't even a requiment that the breakers be installed next to each other. You can use circuits 1, 9, and 17 as a multiwire branch circuit just like you use circuits 1, 3, and 5.
Don

Just MHO, but I can agree with the handle ties. I work and have worked several places where multiwire ckts are the norm (industry and a hospital), have been bitten twice from a shared grounded conductor, & when the line is down it is real hard to remember if the ckt is a shared one or not.

Don

That makes more sense to me now, you will not lock out breakers that you do not know are related.

Perhaps a code change to identifiy multiwire branch circuits?

I prefer to go the 1,3,5 route but we do have formen that will use 1,9,17 etc.

Also are you saying I am required to lock off all 3 breakers even if I am working downstream of spilting off to two wire circuits?

Thanks, Bob

I had one inspector say that I could not run a multiwire to a single dishwasher/disposal duplex receptacle. I looked up the code article, which stated that this practice is ok as long as a two-pole breaker is used. I made a short write-up on the situation and gave it to my boss (who was unlicensed and will always remain so) to pass on to the inspector. Instead, he made the changes required by that inspector because he was afraid to pizz him off!

I emphatically believe that it is wrong to allow an incompetent inspector to get away with these practices. He/she is probably getting paid far better than I and should at least use a small portion of that high-dollar time to show me the code I have supposedly violated. To turn your back or be complacent means your fellow tradesman may find himself in the same situation in the future. Point out the inspector's mistake now (in a sane manner) so that no one else will have to. Passing the buck is lazy and inconsiderate.

Bob,
I think that you must lock out all of the hots to the multiwire branch circuit before working on that circuit. There is always the possibility that the grounded conductor would become open between you and the panel leaving you with a "hot white wire".
Don

This is not a possibility if you are working down line from where you split.

We will often bring multi wire branch circuits out to a jbox in the ceiling of retail buildings, from there we use 2 wire circuits to separate pipe drops to gondolas (shelving) If I need to work on one of these why would I need to lock out the other two?


Bob

Bob,
If the grounded conductor(of the two wire branch) is still connected to the panel and there are loads on the other hots on this multiwire branch circuit and the grounded conductor becomes open between the active loads and the panel, you will be left holding a hot white wire that you think is not energized.
Don

Don

I know sometimes I can be relentless about things and I thank you for your patience.

I understand how this can happen in the electrical sense, but how would this happen in the field.

I am working on the two wire portion of the circuit and a neutral is going to open between me and the panel on it's own?

If we have to think in that way we should lock out an entire panel feeder when we work on any branch circuit.

If I am working on a branch circuit at the same time the panel lost its neutral I am going to end up with a live neutral again.

Bob

Office cubes or free standing hazard. The office cube argument about if you tie the breakers, then when one circuit goes out you loose all the circuits. Yup you do lose the other circuits, but you may save a 20 or 40 million dollar building. Just think of all the hazards with 3 wire circuits, and compare that with upset office manager.

Bob,
Yes that too can be a problem, and I don't really know where to draw the line. I keep telling the people at work that we have to lock out the 33kV feeder to the plant to work on anything.
Don

Don, You "Rock" (equal to cool)

Thanks for your time, Bob

LK I know you are an experienced electrician, but I do not think you realize how prevalent multiwire branch circuits are outside of dwelling units.


Can you explain how we are going to loose the building?

All services are essentially multiwire branch circuits.

There is a great savings in labor and material that gets passed on to the customer on a larger project, yes we do get jobs where the specs say each circuit to have it's own grounded conductor and for this the customer has to pay more.

You must think of the scale of the work, an office building may have 100 to 300 circuits per floor. Most with only 1 to 4 outlets on them or about 10 amps of 277 lighting.

What I am really trying to say is, it's all in what your used to doing and to each their own.

Take Care and we all care about safety or we would not spend our off time talking shop.

Bob

Bob,

Had many years in Commercial and High Rise work. It would take pages to tell you the problems with office cube wiring. It's the office furniture design of the older cubes that presented the problems. The heavy use of electronic equipment in these cubes, cause problems in the entire system. I worked for a number of years with power engineers, and the office furniture design engineers to resolve building system problems. Today when electrical distribution
for office use is designed, most but not all of the problems have been resolved. While talking about the contact hazards involved in multiwire circuits, system failure and fire is another hazard in the older cubes and building distribution equipment. What we found going on in the floor transformers, and distribution panel neutrals was something I had never considered, circulating currents, causing temp rise in the system. again it all depends on the design of the system. Good design up front less problems in the end.

[This message has been edited by LK (edited 09-20-2003).]

[This message has been edited by LK (edited 09-20-2003).]

Don's continuing reference to "multi wire branch circuit" goes a long way here.

Note he never said "circuits" this means one circuit.

A "multi wire circuit" may be considered more than one circuit but is recognized as one circuit.

With that said, any electrician should recognize a multi wire circuit in a box and would be red flagged by more than one ungrounded conductor in the presence of one grounded conductor.

All wiring downstream of the split would be a two wire circuit.

Roger

LK point taken and I am sorry I did not know your past background.

The way it is now we are running 200% neutrals and I think the term is "K rated" transformers. (or is that the shielded ones?)

I can see that when all these non-liner loads where introduced to the old building systems that could cause trouble.

Now with the furniture using a 10 white with 12 hots and many labeled for 15 amp OCP I do not see any problems with overloaded neutrals.

Bob

Bob,

Yes, they have improved the cube systems, and the K rated transformers help Q things up, however there are still plenty of those old cubes in use. Multiwire circuits are ok if, used for the right application.

Les

Get ready for it....

In Canada, it has been a rule since at least the '80s when I started the trade.

All circuits sharing a neutral, in residential, shall be two pole or have tie-bars.
I always assumed it was so when a non-electrician wanted to turn the power off, he did; 'to the whole JB'. It is only for residential, but I can see the point.