I'm working on a project where the ham station is in the mezzanine of a warehouse where the
tower was installed on TOP of the roof, with a seriously over-engineered mount in the middle
of the building metal structure.
OK.
The entire building has a ground rod ring around it that are connected to a 6" copper strap that
does not NOT contact to the building.
Why isn't it connected to the building? Are you saying the ground ring around the building is there only as a ground for the shack? If it isn't not bonded to the electrical service ground, that is a code violation, and is bad in several other ways.
The copper ground strap comes up along the outside side of the building, galvanically isolated, through a plastic tube and junction box, into the shack.
This is crazy. The ground ring is a grounding electrode and MUST be bonded to, and become part of, the service ground. The service ground MUST be bonded to the building steel; hopefully it already is, but verify.
The structural steel of the building is a MUCH MUCH MUCH lower-resistance and lower-inductance path to ground than a piece of copper strap. And, per above, if that ground ring isn't bonded to the service ground, it's only creating new problems. The building steel should be used as the grounding conductor for the tower, master ground bar, etc. en route to the ground electrodes. In some cases, the building steel can also serve as a grounding electrode (i.e. in addition to, or as a replacement for, other electrodes such as ground rods, cold water pipes, ground rods, et al), but without knowing the construction of the building and foundation I wouldn't blindly count on that, so just treat the building as a grounding conductor and not as an electrode.
To summarize:
Bond the ground ring to the service ground per NEC. The ground ring becomes an additional grounding electrode.
Bond your master ground bar in the shack to building steel using listed clamps.
Bond all of the radio equipment, arrestors, etc. to the master ground bar.
It sounds like the tower is already directly connected to structural steel from a mechanical standpoint, but to be compliant, there should be a grounding conductor between the tower and building steel (yeah, I know, seems like overkill).
All feedlines on the tower should have ground kits at the top and bottom of the cable runs, and again at the point of entry into the building if not immediately at the tower base. If the point of entry isn't at or near the master ground bar above, add another ground bar at the entry point for the ground kits, and bond it to the building steel in the same manner as the MGB.
--- Jeff WN3A
KB9LFZ