NEC code for 42 space box - Electrician Talk - Professional Electrical Contractors Forum

frenchelectrican · 03-29-2007, 01:42 AM

I am not sure if i did heard the rumors but if you guys can confermed [ get the facts ] that they are talking to remove the 42 breaker max off the list when the AFCI go on in 08 cycle ??

I did check around but seems i am barking on the wrong tree but if you heard or see the info please do post it here i will like to know what it will affect it.

but i just can't imaged how big the box will be once the code do lift this 42 rules off [ i know it was in effect way back 30's if i read it right due the one of the motel fire long time ago ]

Thanks for your time to read this

Merci , Marc

raider1 · 03-29-2007, 10:26 AM

Marc,

The last that I have seen the limit of 42 overcurrent devices in a panelboard has been eliminated for the 2008 NEC. Here is a copy of the ROP

Quote:

9-117 Log #2643 NEC-P09

Action: Accept in Principle

(408.34, 408.35, and 408.36)

__________________________________________________ _____________________________________________
Submitter:

Kevin J. Lippert, Eaton Corporation

Panel Meeting Action: Accept in Principle

Delete section 408.34.
Delete section 408.35.
Change 408.36 to read as follows:
408.36 Overcurrent Protection. In addition to the requirements of 408.30, a power panelboard with supply conductors
that include a neutral, and having more than 10 percent of its overcurrent devices protecting branch circuits rated 30
amperes or less, shall be protected by an overcurrent protective device having a rating not greater than that of the
panelboard. This overcurrent protective device shall be located within or at any point on the supply side of the
panelboard.
Exception No. 1: Individual protection shall not be required for a panelboard used as service equipment and containing
not more than six overcurrent devices. For the purposes of this exception, the term “overcurrent device” means a single
or a multipole circuit breaker, or a single fuse or set of fuses, operable or disconnectable by a single motion of the hand
and that supplies a single load.
Exception No. 2: Individual protection shall not be required for a panelboard individually protected on its supply side by
not more than two main circuit breakers or two sets of fuses having a combined rating not greater than that of the
panelboard. A panelboard wired under this exception shall not contain more than 42 overcurrent devices. For the
purposes of this exception, a 2-pole or a 3-pole circuit breaker shall be considered as two or three overcurrent devices,
respectively.
Exception No. 3: For existing panelboards, individual protection shall not be required for a panelboard used as service
equipment for an individual residential occupancy.
(C) (A) Snap Switches Rated at 30 Amperes or Less. (No change.)
(D) (B) Supplied Through a Transformer. (No change.)
(E) (C) Delta Breakers. (No change.)
(F) (D) Back-Fed Devices. (No change.)
Panel Statement:

The panel has reworded the exceptions to maintain as much continuity as practical with prior code

practice. Exception No. 1 is based on current 408.36(B) Exception, which is intended to recognize a long standing

practice of allowing a small panel to be used as service equipment, with large line-to-line loads leaving at this point and
a smaller feeder entering the building to supply what formerly was called a lighting and appliance branch circuit
panelboard. The limitations now to be built into this exception prevent the extension of this limited practice to what could
otherwise become a split-bus panelboard of unlimited size in the future. The six-circuit limit echoes the customary
service limitation in 230.71.
Exception No. 2 corresponds to the parent language in 408.36(A). Since prior practice effectively limited these
panelboards to 42 circuits, the wording in the panel action carries that limitation forward, but only for these split-bus
panels.
Exception No. 3 corresponds to present 408.36(A) Exception No. 2, and it continues without change.

I don't think that the panel manufactures are really going to make the panels much bigger then they already are now, but we will see.

Chris

HCECalaska · 03-29-2007, 10:39 AM

i would guess then the only limitation on a branch circuit panel would be maximum disconnect height of 6'6"

MDShunk · 03-29-2007, 10:40 PM

I heard talk that CH has a 60 space box already developed and ready for production. That will help, because we'll probably still have to space out the AFCI's when that big requirement hits, to help with that heat issue.

frenchelectrican · 03-30-2007, 01:31 AM

humm Thanks guys for giving me the straght answer on this one i going to wait and see where the heck it go next when the code go effect

thanks again

Merci , Marc

Pierre Belarge · 04-08-2007, 08:29 AM

the manufacturers already have this product, as Canada has permitted the us of panels with more than 42 circuit breakers...60 circuits is the norm. The panels are UL listed. I would think a few minor changes and here they are

. Lets not forget that in Canada, for service panels there is a barrier so the Service conductors and the feeder/branch circuits are not considered in the same enclosure...a move that should in my opinion be utilized in the US, especially with the big push towards 70E and safety.

JohnJ0906 · 04-08-2007, 08:55 AM

Quote:

Originally Posted by Pierre Belarge

Lets not forget that in Canada, for service panels there is a barrier so the Service conductors and the feeder/branch circuits are not considered in the same enclosure...a move that should in my opinion be utilized in the US, especially with the big push towards 70E and safety.

Agreed. I think it would be safer when it comes to adding circuits or changing breakers

MDShunk · 04-08-2007, 08:58 AM

Quote:

Originally Posted by JohnJ0906

Agreed. I think it would be safer when it comes to adding circuits or changing breakers

I agree also, but the Canadian style boxes that I've seen would create another problem for us. That effectively makes the "feed end" of the box totally useless for bringing in branch circuits, because it's all sealed off. It also doesn't seem to allow you to run the service entrance conductors into the box at the opposite end of the breaker or lugs and run them up through the box. Overall, it's a safer idea, though.

JohnJ0906 · 04-08-2007, 09:01 AM

Granted. However, most panels I've seen recently you can install with the main top or bottom, so I never enter the service cables opposite the main any more.

MDShunk · 04-08-2007, 09:04 AM

Quote:

Originally Posted by JohnJ0906

Granted. However, most panels I've seen recently you can install with the main top or bottom, so I never enter the service cables opposite the main any more.

Me either, but I do often feed the panel at the same end that I'd like to take my branch circuits out of. I could learn to change, in the interest of safety.

JohnJ0906 · 04-08-2007, 09:09 AM

Same here. By the way, Happy Easter!

itsunclebill · 04-08-2007, 10:08 AM

Gees. Hate to pick but couldn't you find a picture of something besides a Federal panel? Even if the breakers have been fixed the buss is still

The primary reason I won't use Sq D unless forced is because their parent company still supports this crap (owns Federal-Pioneer).

MDShunk · 04-08-2007, 11:11 AM

Quote:

Originally Posted by itsunclebill

Gees. Hate to pick but couldn't you find a picture of something besides a Federal panel? Even if the breakers have been fixed the buss is still

:

Over time, you'll notice that most of what I say and do is geared toward generating discussion. The picture of the Canadian style panel was also purposely an image of a FederalPioneer panel.

Carry on

Pierre Belarge · 04-08-2007, 12:44 PM

Regardless of the type of panel, it gives some a good idea of how it is done. Canadians have not experienced the same problems with Federal that us in the USA have, Federal is popular up north.

If we here were to go to installations such as in Canada, we would get use to it, as I do not hear of any Canadians complaining of how they do it. Sort of like how in Chicago, they do not use AC or NMB cable, mostly EMT to install their wiring... I do not hear them complain, just the opposite, they are proud of their work!!!