IG is a big bunch of snake oil anyway. IBM removed this requirement/recomendation from their physical planning guide 25 years ago although there are still data center managers and "tech support" guys who insist on it.
In some very "noisy" industrial installations it may have some value to separate the EGC from the building steel down stream of the MBJ but in most places it is simply wasting your money.
BTW how many of you would say a residence has "conditions of maintenance and supervision ensure that only qualified persons service the installation" per 250.119(B)?
