What does the NEC state about grounding electrodes at a building served by electrical power?

The National Electrical Code (NEC) stipulates that all grounding electrodes that are present at a building served by electrical power must be bonded together to form a single grounding system. This requirement is essential for ensuring that all grounding electrodes work in harmony to provide effective grounding and bonding.

By bonding the grounding electrodes, the system reduces the risk of differences in potential between the different electrodes. This minimizes the likelihood of shock hazards and enhances the overall safety of the electrical system. It also helps to control the dissipation of fault currents, thereby protecting both people and property from electrical faults.

The other options do not align with the NEC requirements: isolation of grounding electrodes could create potential differences that are hazardous, leaving electrodes unconnected would not provide a safe path for fault currents, and while labeling can be important for safety, it is not a requirement specifically addressed in the context of bonding the electrodes.