I have a question about ground grid testing that I am hoping you can answer. I thought I had read in the NESC at one time that there is a 5 year requirement for utilities to test their ground grids. Is this in fact true?
The NESC has no such requirement, and unfortunately, neither does NFPA 70B, of the NETA/Maintenance Testing Standard. Several references to IEEE 80-2000 are mentioned in these best-practice guidelines, where again you find "periodic" as a requirement. The best guidance I can give is that the OSHA General Duty clause could be cited in the case of an injury or fatality, as it is the company's requirement to protect employees from known hazards. If someone were to get shocked or worst case, electrocuted, due to a failed ground grid (corrosion, etc.), then the company could certainly be held liable for lack of proper maintenance, and for not doing "due diligence" in ensuring a properly-functioning ground grid.
For what it is worth, the NESC in section 12, under part 123 "Protective Grounding" does state that "All electric equipment shall have the exposed non-current-carrying metal parts...effectively grounded or isolated. All metallic guards including rails, screen fences, etc., about electric equipment shall be effectively grounded." This is an on-going requirement, thus it is up to the company to ensure that this status is actively occurring. This is again not stating an actual requirement for ground grid testing, but puts the emphasis on the company to ensure such grounds are being maintained.