Wow, this an old thread..... Some names I haven't seen in some time....

Anyway, IMO.... the only time this "HOLE" could be used is if, and only IF the ground conductor is bonded to the neutral for 250.94

Otherwise, I have no idea, the only other time I have ever used one was to put a 1/4-20 in it for a lug. Used to have a boss who would like to feel under there for a nut. No pun intended.... [Linked Image] So he would know I used a lug, instead of those crappy bonding do-dads the panel came with.

But even though the hole fits a conductor great, as some of might know, it would have a inductive 'choke effect' on any current during a fault on the conductor. And although allowed by code, it is a bad practice in some peoples minds.

Mark Heller
"Well - I oughta....." -Jackie Gleason