Two main panels and more than 6 throws total

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68Malibu383

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Raleigh, NC
This house had two main panels, one on each side of the meter. Additional single-pole circuits have been added to these panels during the 35 years since the home was built. Each main feeds a sub-panel in the home. One main panel has four throws and one has six. If I understand the rule, this situation is okay since each of the two service entrances is protected by no more than six throws. Just want to double-check because years ago in a CEU class, the instructor said that a house can have no more than six throws to cut all power off to the home and I've never seen more than six total even with two main panels like this.

What is not right though, is that with this configuration, all breakers in the main panels must be double-pole, correct?
 
Do the panels on each side of the meter have mains or are the MLO ?
 
You are correct that per 230.71 you can not have more than 6 disconnecting means (each can be one, two, or three pole)
Assuming the original installation was Code compliant, it is also possible that a panel or set of service conductors are now overloaded as with a MLO service panel you are depending the
load to limit your ampacity. The person adding the breakers may well have not calculated the effect of the added load to the supply conductors.
 
It is possible that a main breaker kit can be added to at least one panel to make it compliant but as it stands it is not compliant.

The code allows 6 disconnect per service. You have one service as the service is determined by the conductors run from the utility to the house. One drop or lateral equals one service regardless of how many panels or meters that there are.
 
OK go to 230.71(B) and look at the informational note. That note will send you to 408.36 Exception No.3.

408.36 Ex.3: For existing panelboards, individual protection shall not be required for a panelboard used as service equipment for an individual residential occupancy.

Everyone argues with me about this, but I believe that it says what it say.
 
cowboyjwc said:
OK go to 230.71(B) and look at the informational note. That note will send you to 408.36 Exception No.3.

408.36 Ex.3: For existing panelboards, individual protection shall not be required for a panelboard used as service equipment for an individual residential occupancy.

Everyone argues with me about this, but I believe that it says what it say.
Click to expand...
I think this exception basically allows an existing "split bus" panel to remain in existence, but you still are limited to six "mains" even if you can fit more then that into the panel.
 
68Malibu383 said:
This house had two main panels, one on each side of the meter. Additional single-pole circuits have been added to these panels during the 35 years since the home was built. Each main feeds a sub-panel in the home. One main panel has four throws and one has six. If I understand the rule, this situation is okay since each of the two service entrances is protected by no more than six throws. Just want to double-check because years ago in a CEU class, the instructor said that a house can have no more than six throws to cut all power off to the home and I've never seen more than six total even with two main panels like this.

What is not right though, is that with this configuration, all breakers in the main panels must be double-pole, correct?
Click to expand...
Some things have changed since your CEU class years ago - one being the elimination of "lighting and appliance panelboard" definition. When we had that it did put some limitations out there we no longer have - in particular a single pole breaker would have been prohibited as a main disconnect because just having the single pole made it a lighting and appliance panelboard and those were required to be protected by a single main.

Otherwise a typical single family dwelling - six service disconnects max is mostly expected- not often do you run into exceptions of different voltage, phase, frequency, or other characteristics that would allow for additional services. If you do have those things you can have six disconnecting means for each exception. You possibly could run into exceptions allowing a seventh for something like a fire pump or emergency system, though still not all that typical in a single family dwelling
 
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