Square D Split Buss Panel

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ACP

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I am having a hard time locating in the NEC 2011 whether or not the old Square D QO split buss load centers meet code for a single family dwelling unit. They do not have a single main breaker.
 
Over here, across the St. Croix, as long as the split bus panel is installed to the Code of its day, and hasn't been altered, there is no part of the 2011 NEC that retroactively says that the old split bus panel is "non-Code".

Remember, the NEC is a "new construction standard" only.

The most common alteration that tends to happen over the decades after the original install is that some installer puts more than six disconnects in the "service disconnect" section of the panel.
 
Over here, across the St. Croix, as long as the split bus panel is installed to the Code of its day, and hasn't been altered, there is no part of the 2011 NEC that retroactively says that the old split bus panel is "non-Code".

Remember, the NEC is a "new construction standard" only.

The most common alteration that tends to happen over the decades after the original install is that some installer puts more than six disconnects in the "service disconnect" section of the panel.

Typically we find single pole breakers galore in all the previously open spaces.
 
That was my understanding as well. However isn't the 6 disconnects out of code for a single family dwelling? I thought code only allowed 2
 
That I don't know for sure. Typically I run into them on early 80's houses
OK.

The split bus panel, in dwellings, became popular all the way back in the early Sixties when the minimum dwelling service size was increased to 100 Amps. A split bus panel, with breakers no larger than 60 Amps, can supply a large calculated load, yet avoid the price bump for a 100 Amp or larger single main disconnect. Cost conscious hardware purchasers chose split bus panels from the Forties into the Eighties.

The whole time, the "maximum of six disconnects" NEC rule applied in dwellings, unless there was local ordinance to the contrary.

It's only in the last few Code cycles that the dwelling allowance for number of disconnects was restricted to a single disconnect. (I was looking for the citation, but can't recall it at the moment. . . maybe someone reading this can quote it?)
 
ACP,

Found it. A careful read of 2014 NEC 408.36 Exception No. 1 yields what I refer to above. The Code says a second bus structure within the same panelboard assembly shall not be supplied by one of the three or more overcurrent protective devices of that panelboard assembly.
 
OK.

It's only in the last few Code cycles that the dwelling allowance for number of disconnects was restricted to a single disconnect. (I was looking for the citation, but can't recall it at the moment. . . maybe someone reading this can quote it?)

Found it. A careful read of 2014 NEC 408.36 Exception No. 1 yields what I refer to above. The Code says a second bus structure within the same panelboard assembly shall not be supplied by one of the three or more overcurrent protective devices of that panelboard assembly.

But that is a different issue. There is nothing restricting having 2-6 service disconnects in a dwelling unit.
 
But that is a different issue. There is nothing restricting having 2-6 service disconnects in a dwelling unit.
Wellllll. . . . First, I understand your point about the six disconnect rule still being valid as long as there isn't a split bus. I could have said it better in my first post that you reference in your post above, IF I had found the Code citation while I was writing it. I missed this change in 408.36 Exception No. 1, which I believe happened first in the 2008 edition, and have just been learning about it myself.

As for restricting the number of disconnects. . . and also speaking directly to the OP question about OLD split bus panels, the Code is silent about existing installations of old split bus panels. Old split bus panels, installed to the Code in effect during their installation, are still acceptable by today's NEC.

The "penny pinching thinking" that lead many to choose and install the old style split bus panels is where, in my opinion, today's practical restriction of the number of service disconnects comes from, not the Code.

For NEW installations in average single family dwellings, where there is only a single service center housing the Service Disconnect, the Main Bonding Jumper and all the overcurrent protection for all the dwelling branch circuits, there is a de facto restriction of the assembly that eliminates the possibility of a split bus and restricts the service disconnects to the included single main breaker because, with careful material purchasing, one can get the best price with a single main breaker service. Maybe that's not your experience, but it is mine.

Now, IF I could wire a new dwelling with only six branch circuits, I could install a single panel limited to six breaker positions and choose a main lugs only bus to land the service entrance conductors on, but, for any average single family dwelling I've been involved with, there are way more than six branch circuits.
 
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