In this episode of “EC&M Tech Talk,” Randy Barnett, an electrical instructor, trainer, inspector, journeyman electrician, and safety expert, walks viewers through the concepts of grounding and bonding. Initially concentrating on NEC requirements, Randy then demonstrates practical applications not found in the Code.
Randy begins with an introduction to Article 250 of the NEC, Grounding and Bonding. Using correct terminology and understanding the “why” for grounding and bonding is explained using Sec. 250.4. From there Randy moves through each of the 10 Parts of Art. 250. The key to finding the installation requirements is to first ask yourself: “What is my question about?” Then, know which Part will lead to your answer.
Rebar is often used as part of the grounding electrode system in many industrial applications. Randy conducts resistance readings on a small length of rebar demonstrating some unexpected results. Placing rebar in concrete makes all the difference!
Not all grounding and bonding requirements for industry are found in the NEC, however. Randy baits those watching the video by asking about the use of a rubber hose for bonding! The question is answered as he demonstrates the use and measurement requirements for vacuum truck hoses required for use in petroleum operations. If you move flammable liquids through a hose, understanding this part of the video is a must.
Finally, Randy demonstrates and discusses the use of an earth clamp meter to measure the resistance of the ground connections and grounding electrode system. Compliance with the maximum resistance requirements, whether specified by the NEC or other applicable standards, is necessary for safety.
Check back for next month’s edition of “EC&M Tech Talk,” which will focus on making sense of NFPA 70E and electrical safety requirements.
Barnett is the electrical codes and safety program manager for NTT Training in Centennial, Colo.
