"Main breaker" and "main panel" are not the same thing. A main-breaker panel is one which has a single large circuit breaker that disconnects the panel bus from the source of power. A main-lug panel does not have this. Either type can be used as either a main panel (connected directly to utility power without a disconnect ahead of it), or a subpanel (fed by an upstream disconnect). A main-lug panel used as a main panel must have 6 or fewer disconnects in it.Thanks Guys, if I am understanding you correctly, I could install a main panel off my main panel and it would be called a sub panel because it does not contain the main service feed?