This should further my point on installation of GEC at the outside service entrance:
“Having established that the general purpose of the grounding electrode system is to provide a path to ground for high-voltage surge currents and lightning strikes, keeping the grounding electrode conductor outside the building would be common sense. However, the
NEC does not require this conductor to be routed outside of the building.
For example, if a concrete-encased electrode has been installed on one side of a building and the service on the other side, an electrician could install the bare grounding electrode conductor up the side of the building, through the attic, and down to the service equipment on the other side. In this case, any current from surges, lightning and unintentional high voltage would then be routed along the grounding electrode conductor connected at the electrical service, through the attic, and down to ground on the far side of the building. This could create a very dangerous situation with the possibility of fire and destructive voltages in the building.
Understanding the basics for grounding electrode systems should prompt the installation of grounding electrode conductors on the outside of the building or in the ground surrounding the building rather than inside, whenever possible.
EC”
From link:
http://www.ecmag.com/section/codes-standards/grounding-electrode-conductors-building
The AHJ should fail this installation example. It might not obvious violate the code but the long GEC looses its usefulness and even posing fire hazard. To be able to respond fast to high frequency current of lightning strike or voltage surge, GEC should have very small impedance, which requires short length and larger gauge wire, and install in a straight line as possible. High frequency current doesn't like bent wire just like race cars on race track.