ECN Forum Forums Code Related Discussion NEC & other Code issues Interpretation of Article 210.4 (B) - 2008 NEC

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.