What is the target ground resistance for a Type B2 Extra Duty Site?

• A. 5 Ohms
• B. 10 Ohms
• C. 25 Ohms
• D. 15 Ohms

Answer: (A)

Keeping the grounding system’s resistance very low is essential because it gives a fast, low-impedance path to earth for fault currents and stray currents. For a Type B2 Extra Duty Site, the target is five ohms, ensuring touch and step voltages stay within safe levels and protective devices trip quickly to protect people and equipment. Using a higher resistance, such as ten, fifteen, or twenty-five ohms, would raise the fault voltage and slow fault clearance, increasing safety risks and potential equipment damage. Achieving the five-ohm goal typically involves a well-designed network of ground rods and a grounding grid, tested with proper earth-resistance methods to verify compliance.