The Garage is a Completely Separate Building Structure. You MUST have a Disconnect coming in. The GROUND BAR, is so that you don't have half of current flowing into the NEUTRAL and the GROUND WIRE all the way into the house. Or perhaps in a CIRCULAR MOTION. You also have to keep SEPARATED THE GROUND AND NEUTRAL BARS. in the Subpanel for the same reazon. You don't want the Ground wire to have electricity going back in the house. The Bushing is to protect the conductors, when you FIRST run the wire in. Have a Nice Day. [Linked Image]