Built 120/208 bank. Spec had a ferro switch. Floating neutral bus.

[rob8210]

You don't need a floating neutral on the high side when the secondary is a wye voltage. Essentially in a 120/208 3 phase bank each can is hooked up individually just like a single phase can, the 3 phase voltage is taken from leads out of 2 cans . Of course on a single phase can the primary neutral is grounded. The fella that made the drawing must have been confused by the cans having 2 insulated primary bushings. Now if you are in an area that used to have delta primary, then maybe that is an old spec that has never been updated. There is no advantage to floating the primary neutrals on a 120/208 bank , in fact the specs your using cost more to build due to unnecessary equipment.