Limit to number of circuit breakers in panel

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sw_ross

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Kinda think I remember reading something about a change in the limit to number of CB's in panel? But can't find anything now that I'm looking for it. Was I imagining that?

Additional Q- if the limit was/is 42 why do most manufacturers make 40 space panels?

Where did the number "42" come from? Why not 48 or 50?

Just curious!
 
Eaton makes an 80 circuit panel. I know it’s crazy. I have never found the number “42” in the code book. At least the 2014 NEC. I had questioned this as well. I could only find that I had to use the calculated load and the manufacturers recommendations. This was for a single phase 200 amp rated panel.

Jim
 
jksmith82 said:
Eaton makes an 80 circuit panel. I know it’s crazy. I have never found the number “42” in the code book. At least the 2014 NEC. I had questioned this as well. I could only find that I had to use the calculated load and the manufacturers recommendations. This was for a single phase 200 amp rated panel.

Jim
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2005 NEC:


408.35 Number of Overcurrent Devices on One Panelboard
Not more than 42 overcurrent devices (other than those provided for in the mains) of a
lighting and appliance branch-circuit panelboard shall be installed in any one cabinet or
cutout box.
A lighting and appliance branch-circuit panelboard shall be provided with physical means
to prevent the installation of more overcurrent devices than that number for which the
panelboard was designed, rated, and approved.
For the purposes of this article, a 2-pole circuit breaker shall be considered two
overcurrent devices; a 3-pole circuit breaker shall be considered three overcurrent
devices.
Click to expand...
 
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I very much appreciate that information. Not only did I not find it, I have spoken to 2 different inspectors about this. The job I am on has 2 of them. Both said the same. Manufacturers specs. Any idea on how Eaton can market the 80 circuit panel? I will have to find the link and post it. Once again thanks. Have an awesome night.

jim
 
As I recall from previous classes, long ago. The 42 count limit on overcurrent devices was based on heat generation when they used fuses exclusively in panelboards. The heat buildup was a concern when heavily loaded in one enclosure, fuses melt from over temperature as well as they do from over current.

It became the testing standard, and followed on into the breaker age, until 2008 as mentioned previously.
 
It looks like 408.35 was omitted in the 2014 code. But 408.36 does talk about 42 over current devices, but only on an exception.

Jim
 
408.35 was two codes cycles ago.

If you'd like to debate code, this is a no brainer

If you'd like to debate manufactures influence and rationale juxtaposed to theory or real world applications, this could be a loOOOng thread

~RJ~
 
romex jockey said:
408.35 was two codes cycles ago.

If you'd like to debate code, this is a no brainer

If you'd like to debate manufactures influence and rationale juxtaposed to theory or real world applications, this could be a loOOOng thread

~RJ~
Click to expand...

Two cycles ago? :)
Are you still on the 2011?

2005
2008
2011
2014
2017
 
jksmith82 said:
I very much appreciate that information. Not only did I not find it, I have spoken to 2 different inspectors about this. The job I am on has 2 of them. Both said the same. Manufacturers specs. Any idea on how Eaton can market the 80 circuit panel? I will have to find the link and post it. Once again thanks. Have an awesome night.

jim
Click to expand...
Square D has 84 circuit panels, as well as some 60 and 72 from what I recall. I have used some of them. I wouldn't be surprised if GE and Siemens have some over 42 spaces either.
 
I remember the Square D panel. 80 or so circuits. What impressed me about that panel was it actually had enough room on the bus bars for all the neutrals and grounds that the panel can hold.

Jim
 
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