Thank you for your excellent question regarding requirements for maintenance of grounding systems. This is of course a fundamental issue governed by numerous standards, the Engineering Code of Ethics (state law) and in the Code of Federal Regulations.
At the Federal level, we can find maintenance requirements in numerous sections, however the Code of Federal Regulations Title 29 Subpart S – Electrical 1910.303, does in fact mandate maintenance of all aspects of electrical systems, including the grounding. One other section that comes up often is 29 CFR 1910.269(a)(1)(i) which governs maintenance for generation, distribution, and transmission of power, which for a campus of 40 buildings would certainly cover your facility. To go over all the aspects of Title 29 would take a career, and rest assured many a lawyer has in fact made a career out litigating the lack of maintenance of electrical systems.
The other governing code is NFPA 70, the National Electric Code. While the code itself does not specify any specific maintenance, it does demand that your electrical systems are in compliance at all times, which assumes that you are maintaining them. This is similar to how the ANSI-TIA-EIA-J-STD-607-A “Commercial Building Grounding (Earthing) and Bonding Requirements For Telecommunications” handles it’s maintenance requirements as well. For these standards your maintenance procedures are up to you on how to best maintain your systems.
There are some other standards that do specifically call out maintenance requirements for Grounding Systems:
A. Motorola R56 Appendix D – Requires that testing & verification include 3-point fall-of-potential and/or clamp-on resistance readings, along with soil resistivity data to ensure that the ground system is working properly.
B. MIL-STD-188-124B Grounding Bonding, Shielding – Requires in 4.1 that personnel be protected from voltage differentials through low impedance ground paths, in 18.104.22.168.2 an earth resistivity survey is required, and in 22.214.171.124.7 resistance checks of the ground system are required at 12 months after installation and then every 21 months thereafter.
C. NFPA 780 Standard for the Installation of Lightning Protection Systems Annex D, Inspection and Maintenance of Lightning Protection Systems – The 2008 version of this standard has an entire Annex dedicated to the topic of maintenance. This standard requires documented procedures and record keeping. The maintenance required includes visual inspections for corrosion, damage, and lightning strikes. Measurements of ground resistance of all electrodes, and tightening of clamps. Some groups interpret the clamp tightening requirement to include the need to measure the actual tightness using a torque meter and to record the results. Some also interpret the code to require DC continuity testing of the system. All of this typically done on an annual basis.
D. Internationally, the EU standard (British and EU) for lightning protection BS EN 62305:2006 has become an industry leader. This standard has very detailed and complex maintenance requirements for its grounding systems, including impedance of steel columns, and ensuring that all ground electrodes are at equal resistance when not in a ring formation.
We have designed and been involved in the testing of many facilities and compounds such as yours. We generally recommend some combination of Soil Resistivity testing, Resistance-to-Ground testing of the electrode system, computer modeling, and DC Continuity testing, along with a visual inspection of course. Generally, we deal with the above grade lightning systems, computer server room grounding systems, and the below-grade grounding electrode system. We even will check out the internal wiring of electrical panels to ensure that they are properly grounded. Often the DC Continuity testing includes not only the lightning protection systems and the ground electrode system, but also the electrical cabinets and server room grounding as well. The goal of course being to ensure that low-resistance paths exist for these critical components.
We hope you find this information useful.
The Engineering Team at E&S Grounding Solutions