NEC Compliant Ground Electrode Systems
The long-term integrity of the electrode/conductor connection is critical to ground electrode
system performance. The ground rod and the ground conductor bond is fundamental to a long
term, low resistance ground system. Selection of a proper system is mandated by UL 467 NEC
250, which requires careful coordination of components to avoid dissimilar metals and their
resulting galvanic corrosion problems.
Fifty plus years ago, UL defined a full 0.500", 10 mil copper bonded steel rod as the minimum non
ferrous clad ground electrode to bear the UL marking based on testing by the National Bureau of
Standards from 1910 -1955 that confirmed its long service conducted. The full 1/2" and the more
common 5/8" 10 mil 8 foot UL Listed copper ground rod have served the industry exceptionally
well, providing a 40+ year life, typically 4 times that of a ¾” galvanized ground rod.