Ground rods must be buried to satisfy which condition?

• A. Below permanent moisture level
• B. Below the frost line
• C. Below permanent moisture level AND/OR penetrate below the frost line
• D. Above finished grade

Answer: (C)

Grounding works best when the electrode is in soil that can conduct electricity consistently. If the soil at the surface is dry or frozen, resistance goes up and the grounding path becomes unreliable. That’s why the rod must be buried deep enough to reach soil that stays moist (permanent moisture level) or deep enough to go below the frost line, so it remains in unfrozen ground. Either condition provides a low-impedance path to earth, which is what a proper ground rod needs. Placing the rod above finished grade would not meet these conductive conditions.