Mike Dolt Enterprises
Mike Dolt Enterprises
User: walton, Location: Sacramento, CA
Asked on: Wednesday, June 1, 2011 at 3:50 pm EDT
Answered on: Tuesday, May 14, 2024 at 6:05 am EDT
Question: I have a project where we are upgrading 11 Water Agency SCADA sites. The sites are pumping stations for well water and have utility supplied electrical services with MCCs. The design calls for 20' of #4 cu wire and a ground rod to be installed in the concrete pole base and attached to the grounding post in the antenna pole handhole. I asked the question to the PE as to whether the grounding electrode of the new antennas should be attached to the grounding electrode system of the existing on site electrical service per 810.21. The answer was no "because there is no building (structure) on site there is no need to connect the grounding systems per 810.21." I say the Service Panel and MCCs are a structure and the grounding stystems should be connected per 810.21. What do you think? Not that I will change the PE's mind but just want a second opinion.Thanks
Interpretation of NEC 810.21
NEC 810.21 requires that the grounding electrode system of an antenna be connected to the grounding electrode system of the building or structure to which it is attached. The term "structure" is not explicitly defined in the NEC, but it is generally interpreted to mean a permanent, fixed construction that provides support or enclosure.
Application to Pumping Stations
In the case of the pumping stations, the Service Panel and MCCs are permanently fixed to the concrete pole base. They provide support for the electrical distribution equipment and enclosure for the electrical conductors and components. Therefore, they meet the general definition of a "structure" as defined in the NEC.
Grounding System Connection
Based on the definition of "structure," the grounding electrode system of the new antennas should be connected to the grounding electrode system of the existing electrical service per NEC 810.21. This connection ensures that any electrical faults or lightning strikes are safely dissipated into the earth.
Conclusion
Your interpretation of NEC 810.21 is correct. The grounding electrode of the new antennas should be connected to the grounding electrode system of the existing electrical service, as the Service Panel and MCCs meet the definition of a "structure." Flag for review