What is the minimum length of a ground rod?

• A. 8 ft
• B. 6 ft
• C. 10 ft
• D. 12 ft

Answer: (A)

A ground rod must reach deep enough into the earth to contact moisture-rich soil so it can provide a low-resistance path to ground. Eight feet is the minimum length that reliably puts the rod into deeper, moister soil in many environments, which helps keep grounding impedance within acceptable limits. Shorter rods, like six feet, often don’t reach those conductive layers and can result in higher impedance, reducing the effectiveness of the grounding system. Longer rods, such as ten or twelve feet, are acceptable and can further lower resistance, but they aren’t required to meet the minimum standard.