Welcome. My name is XXXXX XXXXX would be glad to assist.
Is the garage attached to the home or a separate structure?
Will post both situations.
Above based on 2011 National Electric Code
Just hit reply for any clarification, thanks
The garage is a seperate structure. So if I understand correctly #3 thhn can be used. This is a direct burial wire and does not require conduit correct? A heavier wire will work as well correct?
THHN is not direct burial, it has to be in conduit. An XHHW quad cable is direct burial. Yes, bigger is fine never a problem.
USE is a service type cable for in ground and an option, not sure what supply houses you have in the area
CLICK HERE is the in ground type cables to give you an idea
#4 is to small correct?
Yes, it is too small correct
What size is the ground wire between the panels