Underground water pipe can serve as grounding electrode if in direct contact with earth for how many feet?

• A. 10 ft or more
• B. 1 ft
• C. 5 ft
• D. 15 ft

Answer: (A)

Grounding relies on providing a solid path to earth for fault current. A buried metal water pipe can serve as a grounding electrode only when it has a continuous metal path that is in direct contact with the earth for the minimum length defined by the standard. That minimum length ensures enough contact and a low enough impedance to earth so fault currents can dissipate safely. If the pipe has been in contact with earth for less than that threshold, it isn’t considered a reliable grounding electrode. Any pipe that meets or exceeds the minimum length qualifies, including those longer than the minimum. Among the options, the one describing the minimum length or longer best matches the requirement. The shorter lengths do not meet the standard, while a longer length still satisfies it.