I have always been under the impression that a detached garage at a dwelling does not require a main disconnect at the garage eventhough it has a panel that has more than 6 branch breakers. However, one of my students said that 225.32 applies.
but my defense was article 408.36 the main overcurrent device for a panel board can be located within or at any point on the supply side of the panel board.
The more I read 225.32 the more i agree with him that a main disconnect is required st the detached garage.
The only time you don't need a main in a detached building is if you can meet the "documented safe switching procedures are established and maintained for disconnection, and where the installation is monitored by qualified individuals" test. That is not most places. I have only allowed this a couple times. Once in a DOT maintenance yard and a few times in prisons. 408.16 pretty makes the "6 throw" rule "two" in most cases anyway.
Especially with the common conversion of garages into shops, etc ... there still remains one little detail: there is almost always at least one circuit there that is not fed from the garage, and can't be run through any panel that might be in the garage.
I'm referring to the outside lights. It's very common for these lights to be on the same circuit, and controlled along with, the lights on the outside of the house.
The end result is that you can kill the panel, and still have power in that garage. There may not even be a switch at the garage for these lights.
I don't think the code addresses this situation at all.
When I did my service upgrade the new main was in the garage and fed the house as a sub. That gave me access to plenty of power out there from the main. I did leave the existing circuit in the garage that handles the overhead lighting and the door opener. That way, if I have someone snooping around in there I can put them in the dark from the house and keep the overhead door from opening. Walking around in my garage in the dark could certainly get you hurt