In article , stryped wrote:

What I dont understand is why the need to separate the neutral bus and
ground as they all end up combined in the main panel anyway.

Because the neutral conductor _carries_current_. If you combine neutral and
ground anywhere except in the main panel, then all of your ground conductors
*everywhere* are carrying current also.

Also, I always heard it was bad to have multiple ground paths. If I
have a ground rod for the house and one for the detached garage, arent
these all connected? All sub panels will be attached to the house
ground and the sub panel in the detached garage will also be attached
to another ground rod. AM I misisng something?

Yes, you're missing a basic understanding of residential electrical wiring --
which is why a number of people have told you to hire an electrician.