Comparing Grounding Test Methods in the Field

In an effort to find out how grounding test equipment and methods compare to their presentation theme on “Apples to Oranges to Banana Pudding,” EC&M Editor-in-Chief Ellen Parson sat down with Lee Howard, Sr. Project Manager, and Jacob Rioux, Grounding Specialist with Hood Patterson & Dewar, to go over the key takeaways from their session at PowerTest26, hosted by NETA, the InterNational Electrical Testing Association, on March 2 in Nashville. Incorporating the latest codes and standards updates, the duo’s presentation explored how different grounding test methods — including fall-of-potential, computer-based ground multimeter, and current injection testing — each have unique advantages and limitations depending on the application. During the conversation, Howard and Rioux also discussed the complexities of testing grounding systems that reside underground, the practical differences between overhead and overland current injection testing, and the logistical and cost challenges that arise when testing in dense or urban environments. They also emphasized a common misconception around fall-of-potential testing — noting that relying solely on the 62% rule can produce misleading results if a full resistance curve is not developed through multiple measurements. Without proper testing methodology, interference from electromagnetic and radio-frequency sources can compromise data accuracy. The discussion also highlights what electrical contractors and engineers should understand about the 2025 revision to IEEE 81 as they work to verify grounding system performance safely, accurately, and cost-effectively in the field.