house panel has no main breaker

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suemarkp said:
Yes. They made "split bus" panels that had 12 slots for double pole breakers (usually the top as slots) and those 6 breakers were your service disconnect. One of these would feed the lower section of the bus and was typically a 50A or 60A breaker. Both houses I had with panels like that labeled the breaker feeding the lower bus as "main" even though it isn't really a single main.
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I've seen those before in older houses. The proper term for the breaker that feeds the lower section is "Main lighting". A modern panel would have just a main breaker (not a main lighting one).
 
JoeNorm said:
So this 6 disconnects only has to do with services? What about when a Main lug panel is being fed from a breaker? Can it have as many breakers in it as it wants?
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If you are back feeding a breaker to use it as a main? As long as it has a screw holding it in place that's fine.
 
Feeders to separate buildings require a disconnect at the building. Those rules are similar to the Service Disconnect rules. A detached building can't have an just an MLO panel -- it needs either a backfed main, a separate disconnect in front of it at that building, or a main breaker panel.

Panels within a building past the service disconnect don't require main breakers. They can be MLO panels with as many breakers as they are rated for.
 
I have compiled this list before, but this what I come up with for situations where you would want/need a MB (note the breaker never has to be within the panel board, but we will assume that is the most convenient):

1. For service disconnect or disconnect for detached structure.
2. When feeding a panel from a tap
3. When feeding a panel from a transformer
4. For series rating purposes
5. Other 408.36 reasons besides #2 & #3
 
Split bus panels are no longer a legal installation with the 2020 code, unless each of the six breakers are installed and protected within their own enclosures.Very uncommon for residential installations. The problem with split bus panels are numerous. If not properly calculated, the sum of the amperage during a fully active panel can add up to more that the incoming wires are rated for.All six upper breakers are required to be labelled as "Main Service Disconnect" though often the labels have fallen off. I also often see added breakers at the top bus with "thins" added to squeeze in greater loads with as many as 9-10 throws to the breakers to shut off all power, thus reducing the safety regarding overloading. There is a strong tendency to abuse this type of panel configuration, though it was legal when first allowed.

Installing a service disconnect with overload protection on the line side of the split bus would satisfy this protection, but that is rarely done and would be better to just use a MLO panel in that case.
 
hillbilly1 said:
Is the panel service equipment? Or
A sub panel? If it is service equipment, and it has less than six breakers FASTENED in, then it’s legal. (Provided it’s not installed where 2020 code is in effect) But if it is a sub panel, it is not required to have a main, unless it is on a different building than the service disconnect.
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Does the 2020 code require a main outside, even if there are 6 or less handles outside ?
 
JDB3 said:
Does the 2020 code require a main outside, even if there are 6 or less handles outside ?
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Yeah, emergency disconnect, I don’t think it has to be fused disconnect or circuit breaker though, if I’m not mistaken. But if you are changing everything, I would use a breaker, then you only need an MLO inside.
 
JoeNorm said:
So this 6 disconnects only has to do with services? What about when a Main lug panel is being fed from a breaker? Can it have as many breakers in it as it wants?
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Yes. The breaker in the main panel is a single handle that shuts off the sub panel.
 
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