Re: Article 210.4(B) - 2008 NEC;
Interpretation of Article -VS- "Intent" of the Article.

Looking for input from anyone in the Design / Applications / Management areas, and especially from Inspectors, Plans Examiners and Code Consultants, regarding the Long-Winded Post below!


On a very large, and very complex Project we have (out of State, not in California), the DBS (Building Department) just adopted the 2008 NEC.
Adopted in entirety, with no amendments, in effect September 1st, 2008.

I Designed / Engineered the areas within "Our Scope Of Work" (there are 3 other E.C.s on this Project - told you it is a big project!), and submitted the Plancheck Set in late August, 2008.
No P/C revisions were requested, nor were any Bulletins or other documents issued by the DBS.

Panelboards, Switchgear & Transformers were supplied and installed by another E.C. (panels, gear, transformers, devices and feeders not in our scope / N.I.C.).

In July, 2008, I submitted Panel Schedules describing the Circuitry + Devices we needed for our Scope, to the Electrical Consultants hired by the Client.
This Firm is to supply the Panels, Gear, Devices and Transformers to the installing E.C.(s) of the project.

Work began on the Project September 8th, 2008, and I am Project Manager for this job.

Now to the point!!!

The DBS is interpreting 210.4(B) to be for _ANY_ Multiwire Branch Circuit - not simply where a MWBC terminates to a single yoke, or in a single piece of Equipment.

Simply stated, all the Multi Wire Lighting Circuits I have Designed on this Project, will require Multipole Common Handle Tie Circuit Breakers, even though no single Fixture will have 2 or more Circuits terminating inside them.

I contacted the DBS to verify the interpretation, and they confirm the above interpretation.

Am I missing the point of the Article, or is this a mis-interpretation by the DBS?

As I understand (and interpret) Article 210.4(B), it's intent is to eliminate the hazard of One (or more) Ungrounded Conductors being left energized on:

* A Single Yoke Device - such as a Receptacle,
or,
* In a single piece of Equipment - such as a Lighting Fixture, having Ballasts connected to 2 individual Circuits;
Example:
1 Ballast from switched Lighting Circuit on CKT #10, 1 Emergency Battery Back-Up Ballast connected to unswitched Lighting Circuit on CKT #12

If separate 1 pole devices were used for the above listed Circuits, a _QUALIFIED_ Person working on the Device / equipment may inadvertently leave one or more 1 pole OCPDs closed, for the MWBC feeding the item, introducing a Ground Fault hazard at the item.

Risk of L-G Ground Fault (shock, short circuit/sparks flying, or both) is dramatically reduced at the single device / equipment by the use of a Multipole or Common Handle-Tie OCPD.

This _DOES NOT_ include Junction Boxes with MWBCs, or multiple Outlets / Equipment where MWBCs will run through, but only a 2-wire Circuit (L-N) terminates on the device, or at the equipment.

This is really a problem for this particular project, as the Lighting Circuits use Lighting Contactor type Circuit Breakers (read: $$$).
Additionally, one of the Lighting Panels is connected via ATS to the Emergency Power System - and the Night Lights / Emergency Lights are derived from that Panel, along with several General Lighting Circuits for common areas.

The "Switched" Gen. Ltg. circuits from that Panel include an Unswitched circuit, for Night Lights / Emergency Lights in the common areas.
These are MWBCs.

A 3 Pole device with Lighting Control feature, will open the unswitched circuit, leaving the Em. lighting to run solely on Battery Back-Up power for > 8 hours.
This, of course, will drain the Batteries in less than 120 Minutes - every day, leaving the egress areas unlit.

Any comments???

Looking for input from anyone in the Design / Applications / Management areas, and especially from Inspectors, Plans Examiners and Code Consultants.

Thanks in advance.

Scott

If this was permitted under 2008 that is what it says.
They deleted the "single yoke" language.

I am going to say you have to use common trip or approved handle tie's.
(Side note: don't overlook 210.4(D) grouping. )

The exact methods of making a multi-wire branch circuit have been the focus of many an internet debate. If you're a fan of scattering the 'legs' all over the panel, all I can say is, in the 2008, "you're busted!"

You have my sympathies. I consider this change to be one of the most far-reaching, profound changes in the 2008 cycle ... a 'stealthy' one that snuck in without anyone catching it. I'm also certain that the panels have received many proposals about it!

Simply put, ALL mwbc's need to be fed from a multi-pole breaker, and the wires need to be grouped / zip tied together in at least one point in the panel - including the neutral.

While I consider these practices to be very good practices, I cannot endorse making them mandatory. IMO, the NEC has crossed over into design issues.

Thank you for pointing out another problem with having the multiple circuits ALWAYS trip together. It certainly makes troubleshooting harder (which one of the three has the problem?), and can defeat the purpose of putting lights and receptacles on different circuits.

Well, I must say that I strongly disagree with this requirement unless a single yoke device is involved. We are supposed to be professionals. We all know that MWBC's must be kept on opposing phases. We know how to work safely with these circuits.

When does the NEC change from being a material of reference to a complete safety manual? There are always going to be idiots out there who don't know how to work safely with MWBC's, but why does the code have to be modified (at significant cost to EC's and their customers) to protect them? Every time someone causes a vehicle accident, the state doesn't rewrite the motor vehicle code do they?

How about AFCI's? Ballast disconnects? Tamper-proof receptacles? Don't get me started on those issues.

Back to the lighting MWBC issue: Look at the inconvenience that this requirement is going to cause a qualified service person. Now, to safely service a single fixture on a group of lighting circuits in an office, 3 times the number of people will be left in the dark. Seems pretty silly to me.

I'm all in favor of doing things safely, but at what point does the code become a guide to prevent unqualified people from hurting themselves? How far must it continue to go?

If you ask me, it's all about the wire manufacturers wanting us to buy more wire and the breaker manufacturers wanting us to buy more expensive 2 or 3 pole breakers. Good old NEC at work; business as usual.

Ed, I feel your pain. BUT....

This code has been available for some time. The period to submit proposals for the next edition has just closed.

I can't speak for others ... but I got MY proposals in. Maybe the code panel will 'see the light' .... I am guessing that their chances of agreeing with me are closely influenced by how many others felt inclined to make proposals similar to mine.

Complaining after the fact makes it all the more difficult to get the panels to reverse their earlier decisions. I agree that this section snookered everyone .... let's hope the panel members are reading this thread.

I take the position of agreeing with the 2008 code on this.

On the face of it, the primary hazard exists with line-to-line loads. You need a means to disconnect all ungrounded conductors into a load to avoid cross energizing. It might seem that line-to-neutral loads are safe in this regard.

However, maintenance of (parts of) a MWBC could involve disconnecting the grounded conductor. In the case of single phase 3-wire, this can result in a hot neutral. In the case of three phase 4-wire, this could create the additional hazard of voltage instability between equipment on the other still-connected phases. Note that this rule applies to the means of disconnect, not the OCPD. It's the disconnect that applies when maintenance is in progress.

I'm sure no one here would ever do such work without disconnecting all the phases, especially if the work might need to break the neutral during progress. But are all the phases even going to be next to each other when single pole breakers are used (on a panel you didn't wire up)? Requiring a common disconnect ensures a grouped disconnect. It also ensures a condition safe for maintenance being applied to the ungrounded conductor (or any conductor).

I suppose the question would be, how do you know you are working on a MWBC if the breakers and conductors are not grouped and handle tied?
This is not usually a problem when everything is fresh but after years of alterations and additions you might "lose" that identification.

I've long been an advocate of finding some way to identify neutrals. I've tried several schemes, but all have had extremely limited utility.

If I can plan the job from the start, many possible sources of confusion can be avoided.

Naturally, several remodels / repairs / modifications later, and all bets are off.

Yet, even the new code provisions will not help, in that I have found multiple 'round robins' tied into the neutrals. This usually happens in a junction box, where the neutrals either get confused, or, more common, they all get landed under a single wire nut.

What we really need is another color for neutral wires!

Yet, all my methods are but 'trade practice.' Useful as they are, I cannot imagine making them a matter of code.

I get the feeling that the code panel has developed a bias against the very use of MWBC's, but has not found the courage to actually come out and say so. I can imagine the arguments; from an academic perspective, it's all too easy to make the case against their use.

Yet, these Ivory-tower arguments all pale in the tangle of a crowded junction box, a cluttered panel, and the difficulty of pulling in that additional wire.

These are some of the reasons I consider this code rule to be 'bad law,' and would like to see it removed.

The 2008 edition of the NEC was pretty profound in the scope of it's changes. We were all so busy discussing AFCI's, then tamper resistant, that some major changes (like this one) got missed until it was too late.

IMO, whether or not to use MWBC's, and how to do them, are design issues, and ought to be left out of the NEC.

This is just another reason I would like to see the NEC on a 5 year, or maybe even 10 year cycle. The TAC could deal with truly bad stuff that slips through but it would be less likely to happen if the cycle was long enough to really analyze changes for a while before you print them and let the current code settle a bit before you change it again. If we were just putting the finishing touches on the 1999 code changes for a 2009 release we would actually have AFCIs that work before we jammed them down people's throats and we would have had time to discuss things like this MWBC thing.
Nobody ever said you couldn't install any listed item like a TR receptacle or an AFCI as soon as it was listed. Leave it up to the manufacturers to sell them to the public. If the public really is convinced this is a good idea we will be happy to put them in.
Could you sell them? Sure, this is the public that buys "green plugs", electronic varmint repellers and "baby on board" signs.

What Greg said.

If I were to design a new bus system for breaker panels (without any need to be compatible with existing ones ... e.g. all new breakers would be made for it, etc), I would design one that runs all current carrying conductors (both ungrounded ones, and the grounded one) to the stabs for the breakers. So the neutral would have its own bus line, too. Each slot position would have a place to stab its distributed phase, and a place to stab the neutral. All breakers would include a terminal for neutral. A ground bus bar would be run on both sides of a dual-column panel.

Given the outlook of more circuits, if not most, being AFCI in the coming years, this kind of panel design would have an advantage. The GFCI and AFCI breakers would not need a pigtail.

With this kind of panel design, running an NM cable inside the panel down to where the breaker is would fill the space less. Everything (phase(s), neutral, ground) can be connected easily at one point. Given enough space for a top or bottom fed panel, or allowing cables to exit on the sides of the panel, it might be feasible to actually run NM inside. Of course it would fill the panel more than singles from a de-sheathed cable would, but it would avoid the confusion of having to follow single wires around.

I don't know what the thermal issues might be doing that. If a manufacturer were to make such a panel design, they would have to do lots of tests to verify the thermal issues of filling it up with NM (or UF) cables. The panel might still have to be made larger than typical home panels are today to be suitable for cables inside.

OTOH, with so many AFCI breakers generating heat, and their pigtails filling the volume, today's panels could still have issues, too.

But, a panel design that did allow cables inside safely, and had everything connectable at one point (all but ground coming from the breaker terminals, and the ground bus right under the breaker), would make grouping easier.

Thanks to everyone for posting your replies to this discussion!

My rant on this particular Project + Interpretation is that the requirement for Multipole OCPDs came _AFTER_ the Plans had passed Plan Check, and the job was fully into Rough.

I had no idea about the Interpretation, until our Field Superintendent on the Project called me for verification of the Article!
He was informed by one of the other E.C.s on the Project per this issue for MWBCs:
"Either use Multipole OCPDs, or run everything as Two-Wire Circuits!"

Two-Wire Circuits are definitely out! Most Lighting Circuits are in Wireways, and current design has maximum of 28 CCCs in any of the Wireways.
Other reasoning is Homeruns.

I just would have liked to know from the DBS that they would be changing to the 2008 NEC, and will enforce that version in the field.
Then I could have arranged with the Panelboards & Gear Vendor / Supplier to reconfigure the Lighting MWBCs.

I sent an RFI to the Vendor regarding the issue, which was promptly sent back to me - with instructions to contact the Project Manager of the E.C. installing the Panelboards + Gear (AKA: Pass the Buck!).

Bounced same RFI to that guy, and received a "You Are Responsible Now" message for reply!

To rectify the issue, we will be installing Approved Handle Ties (Manufacturer Accessories) instead of replacing with Multipole Breakers.
This is an acceptable method per the Article.

FYI:

I do not have the 2008 NEC, which made things very difficult to verify!
California is using the 2007 CEC (California Electric Code), which uses NEC 2005 as Model Code.

To verify the Article, I researched it on the NFPA site.

According to the NFPA site, the Article's intent is as it always has been; to eliminate the Shock hazard of leaving one or more Ungrounded Conductors live on a Single Yoke or Single Piece of Equipment.

Nothing in regards to Open Common Grounded Conductors (Open Neutrals), nothing about multiple Junction Boxes.

Even the first response from the DBS verifying their stand on the Article, had the same text as the NFPA site did, verbatum! (the text was copied / pasted!)

The problems with interpreting 210.4(B) this way are:

*1: Electricians not turning off Circuits to work on a Fixture or Device,

*2: Installing excessive Conductors to eliminate the need of Multipole OCPDs.

Examples:

*1:
Turning off a Multipole Breaker on Lighting Circuits would result in wide spread darkness, not just in isolated areas.

Turning off a Multipole Breaker will de-energize Receptacles on different Circuits than the one to be serviced.

Results: complaining Customers, personnel encouraged to work things Hot, rather than turn off Circuits (even though there is no justifyable reason to work the Circuits hot!)

*2:
Instead of using MWBCs connected to Multipole Breakers, some may decide to install all Branch Circuits as Two-Wire (L-N) Circuits, using anywhere from 200% to 300% more Copper Conductors than necessary;
AND-
Creating derating issues, as each Circuit will have 2 CCCs.

OK, ranting is over!!!

< RANT MODE = DISABLE >

Scott

Naturally, this "improvement" is redundant in lighting circuits, as the fixtures are now all supposed to have a 'disconnecting means.' We'll just overlook the fact that the different disconnects are not interchangable...

Sorry you got blind-sided by the requirement; I was similarily distressed when I first read it. Other codes have given me similarly rude surprises (exit lighting comes to mind).

IMO, this whole "model code" nonsense has become out of control. It's almost as if we're having a contest, to see just how impossible we can make it to comply. That's a topic for another thread, though.

I would have rationalized,All plans and permits were approved and accepted. Prior to the Sep.1/ 2008 deadline.
The project would fall under that code cycle

Lee, I would have to agree with that. Changing code rules in the middle of a project just isn't right.

I was always told that the Code that was to be enforced for the job was the one that was effective on the date that the permit was issued.
What are you supposed to do with a job that takes several years and several Code cycles to build?

Rule here is NEC effective date permit is issued is the Code for the job, cradle to grave.

BTW, when the '08 is posted in the NJ Register....a flurry of resi permits will come in, reasoning to beat the AFCI requirements that are to be adopted. There's a 'grace period' from Adoption date to effective date.

I too, strongly disagree with this requirement in applications other than single yoke devices or other utilization equipment that requires more than one phase conductor. While the desire to make our work hazard-free is admirable, it is, ultimately, unattainable. That this is the justification for such a change is discouraging. I have not been able to find the committee's records as to the nature of the discussions surrounding this change, but it sure seems like the effort is being made to protect the unqualified person from himself or herself...again.

Many have spoken to the numerous problems this change will make with respect to troubleshooting, or general maintenance, or addition/modifications, but what about the unintended consequence of false assurance? How many more changes or restrictions in the name of safety will occur before the amatuer electrician/Maintenance Man/Homeowner believes that his electrical system is intrinsically safe? If we keep this up, we will reach a point where the untrained person, lacking the knowledge of basic electrical principles and practices, exposes himself to potential hazards because he is led to believe, falsely, that he is safe when in fact he is not.

Some might say that we are already there, and that is why we need to make these changes, to protect the unqualified but it seems to me that moving in this direction does more to encourage the unqualified to engage in work they should not be doing than it does to protect them from harm.

Just a reminder .... it's time to comment on the 2011! The committee, as of right now, sees no reason to remove this requirement. Perhaps a 'hue and cry' from the field will help them to reconsider.