The plant manager said he received information that people were getting shocked on ground rods. He wants you to determine if this is true, and, if so, to identify and fix the cause. He said he doesn’t understand how that can even happen. “Doesn’t a ground rod take the voltage to zero?”
When the conversation steered to the severity of these shocks, he said thus far nobody has died or needed medical attention. But he felt this might be a ticking time bomb and it needs prompt resolution.
What are some first steps in solving this?
Start by asking, “Who was shocked, and why were they near ground rods in the first place?”
If the ground rods are:
• On the load side, they were probably installed in lieu of proper bonding. Undesired current is circulating, and thus people touch the rod and get shocked.
• In the utility service area, who is entering that area and why? Lock it down.
• Used for safety grounds, compare the set-up to ASTM F-855 (a protective grounding standard).
Grounding systems inherently have resistance. Thus, current will flow not just through the grounding system but also through anyone or anything in parallel with it. You should also conduct a thermographic survey to find high-resistance connections
