Reno is right about IG.
I was an installating planning rep at IBM for 5 of my years there. Isolated Ground is a waste of money. IBM stopped mentioning it in the Carter administration but the legend lives on in the mind of "experts". If you like the customer, save them some money and talk them out of it. If they really insist, money is not an issue for them so sell them "monster" super neutrals at the appropriate price. Then you can take the family to Hawaii this summer.
