Associate Safety Professional Practice Exam

What is the best method to achieve earth grounding for electrical installations according to the NEC?

1. A wall-mounted grounding rod

2. A metal underground water pipe and connection to a driven electrode

3. A registered grounding machine

4. An insulated grounding block

The correct answer is: A metal underground water pipe and connection to a driven electrode

The best method to achieve earth grounding for electrical installations, according to the National Electrical Code (NEC), involves utilizing a metal underground water pipe in conjunction with a driven electrode. This method is widely recognized for several key reasons. Firstly, metal underground water pipes are typically in contact with the earth over a significant length, providing a low-resistance path for electrical faults to dissipate safely into the ground. This characteristic enhances the effectiveness of the grounding system, ensuring that an electrical fault can be safely managed. Secondly, the NEC stipulates that a grounding electrode system must be reliable and continuous. By effectively combining a metal underground water pipe with a driven electrode (such as a grounding rod), the system ensures redundancy and improved conductivity. A driven electrode can supplement the grounding provided by the water pipe and assist in maintaining compliance with NEC requirements regarding grounding systems. Moreover, this method aligns with code requirements that emphasize the importance of ensuring effective grounding paths for both personnel safety and equipment protection. Overall, using a metal underground water pipe and a connection to a driven electrode stands out as a robust and code-compliant solution for achieving proper earth grounding in electrical installations.