Which of the following is a key principle covered by the NEC?

The key principle covered by the NEC (National Electrical Code) focuses on the grounding and bonding of electrical systems. Grounding and bonding are critical to ensuring electrical safety, providing a path for fault currents to minimize shock hazards, and maintaining system stability. Proper grounding helps to protect both people and equipment from electrical surges and faults by directing excess electricity safely into the ground. Bonding, on the other hand, connects various metal parts of the electrical system to eliminate potential differences in voltage, which could create a shock hazard.

While voltage drop calculations, electrical surge protection, and energy efficiency standards are important factors in electrical installations, they are not core principles directly addressed by the NEC itself. The NEC primarily focuses on safety and effective grounding and bonding practices, establishing guidelines and requirements to ensure reliable and safe electrical installations.