Joe, Here a picture of the full panel. If you count them, there are 58 overcurrent devices. I took this picture before they actually called in their final inspection. When I did get there for the final, there were 68. I should have taken a picture then. They corrected their violation by adding an additional panel beside this one and moving some circuits, but when I went there yesterday, they still had 54 OCD's in the old panel, and the little panel they added is full. They still have some work to do before I can let it go. I'm holding their feet to the fire. This is an electrical contractor!
Thanks, Darryl Dempsey
The "instructions" that appear here are required to be followed in order to show compliance with 110.2, otherwise the job gets Red Tagged.
In big letters, up at the top: G4040ML1200CU. And in the lower corner, Class CTL. Those first few numbers and letters say it has 40 spaces, in which 40 poles are permitted. Class CTL means that it's designed to reject Class CTL tandems, which means that they've either modified the panel to take the tandems, or they're using non-Class CTL breakers.
Also, assuming that this is a "Lighting and Small Appliance Panelboard", the absolute maximum number of poles permitted under the NEC is 42.
Solar, thanks for the explanation. I gather that all lighting & appliance panelboards have "4040" (or other) as part of their catalog numbers, so the problem was obvious to everyone but me
Thanks to your pointer about the "CTL" class designation, I found a page that explained the history nicely: http://www.mikeholt.com/misc.php?id=unformatted/8-29-99&type=u&title=Circuit+Breakers+-+CTL+Assemblies+(8/29/99)
So, I understand now that this is probably a case of using CBs marked "Replacement Use Only - Not for CTL assemblies" in a CTL panelboard.
This is a perfect example of why I lurk here -- I learn something nearly every day.
(Note to "Hitchikers Guide to the Galaxy" fans: Now we know what the ultimate question is!)
John, I don't know whether ALL panelboards use the "4040" nomenclature--as far as I know, there's no provision in the code that requires that. Rather, it's common enough that you can pretty much figure out what the panel is from the number.
There should be a specific mention on the instructions about what is allowed, and what isn't. It may be in the directory part (where "blender" is written in). The diagram in the middle shows only one pole in each position; if a tandem is allowed, the diagram normally shows two poles. I'm thinking that there's some sort of note printed just above the directory that doesn't show in the pictures.
electricmanscott: I wouldn't consider reducing the number to 54 exactly 'correcting the problem'. Plus the issue if the breakers are listed for use in the panel. If I was inspecting, I think I'd want to see some load calcs before I signed off on something like that.
SolarPowered "...With work like this, the guy must be Canadian or something..."
No we would at least use Robertson screws to hold the cover on. :=)
Besides what's the big deal how many breakers you have in a panel? As long as the bus is rated for the current that the Over current protection will allow through I see no safety issue. If we had that code over here we would be putting subpanels in New Houses. It looks a lot neater with one nice size 84 circuit panel on the wall than 2 - 42 circuit panels
Dynamite, I agree with you that the 42 circuit limit seems arbitrary- and should be deleted.
I believe the number of circuits in a panel is a design issue. Personally, I prefer a main panel serving a galaxy of satellite sub-panels. I prefer multiple subs for two reasons: the breaker should be located close to the area it serves, and there is a limited number of openings you can put in a panel case. Using your example, 84 romex circuits would need at least 42 1/2" knockouts- under the best of circumstances, 21 top and 21 bottom. That many holes needs a lot of metal!