The length of bare copper conductor in a ground rig MUST be buried no less than 2.5' below grade and have a length of at least?

For a ground rod installation involving bare copper conductors, the National Electrical Code (NEC) specifies that the length of the grounding electrode, which is often a ground rod driven into the earth, must be at least 8 feet. However, when considering the entire grounding system, local codes or specific installations might require conductors to encompass more length to ensure adequate grounding effectiveness and soil contact for electrical safety.

In this instance, the option indicating 20 feet aligns with common practices in many regions which suggest that using a longer conductor enhances the grounding system's function. This ensures a lower resistance to ground, providing a more effective path for fault currents and enhancing overall electrical safety. Deploying grounding systems with longer conductors is also a safeguard against both environmental changes and corrosion that may impact the grounding effectiveness over time.

While other lengths may also be suggested, choosing 20 feet is a best practice for reliable and effective grounding systems, as this often exceeds the minimum requirements ensuring compliance with various safety standards.