Code Quiz: Ground Rod Resistance Requirements

Nov. 26, 2019

Test your knowledge on driven ground rod resistance.

Question: To comply with NEC requirements, a driven ground rod must have a resistance of ____ ohms or less.

10
20
25
None of the above

See the answer below.

Answer: D

Explanation: Section 250.53 of the NEC requires that any made electrode that has a resistance greater that 25 ohms be supplemented by another electrode. The NEC does not require that an electrode have a resistance of 25 ohms or less, even after the addition of the supplemental electrode. It is worth noting though that many project specifications may have more restrictive requirements.

Lupacchino is a senior design engineer with Gaylor Electric, Inc. in Noblesville, Ind. and serves as an alternate on NEC Code-Making Panel No. 3. He is currently licensed in more than 80 jurisdictions. He can be reached at [email protected].

About the Author

John Lupacchino | Senior Design Engineer

John began his career in electrical construction as an apprentice and worked his way through the trade. He is currently licensed in more than 80 jurisdictions. With more than 35 years of experience, he now plays a vital role in Gaylor Electric’s Engineering Department, where he serves as a senior design engineer. With a focus on design engineering, quality assurance, and code compliance, he has earned the highest level of respect from industry professionals alike. John currently serves as an alternate on NFPA 70 Code Making Panel No. 3. In addition, he enjoys sharing his electrical knowledge through education. As an Associated Builders and Contractors instructor, he continues to help grow a new generation of high-performing construction leaders.