Now my question is?
Is this a service disconnect?
We use the R-3 version of these QO disconnects for trailer disconnects, and as you can see in the photo, there is only one lug for a GEC on the neutral bar, they do make a small grounding bar for it, but it wont take a #4 conductor (which is not needed for a 100 amp service) the only way to do these if you have more then one GEC landing, is to tap the other GEC to the main GEC, the #4 can go into the lug on the neutral bar and using a split bolt tap the #6 to the #4 just outside the disconnect, these disconnects do not have much room in them to tap inside them, and are hard enough to even get the service conductors in them, I have never used one for a service, just a feeder disconnect.