Which NEC article governs grounding and bonding of electrical systems?

• A. Article 310
• B. Article 240
• C. Article 90
• D. Article 250

Answer: (D)

Grounding and bonding across electrical systems are governed by Article 250. This section lays out how the electrical system is connected to the earth (grounding) to establish a reference potential and to provide a low-impedance path for fault currents, and how conductive parts that could become energized—such as enclosures, raceways, and structural metal—are bonded together to keep them at the same electrical potential and minimize shock risk. Grounding gives the fault current a path to return to the source and helps overcurrent devices trip, while bonding ensures all metallic parts are at the same potential so a person won’t touch two different voltages. Other articles serve different purposes—Article 310 deals with conductors and ampacity, Article 240 covers overcurrent protection, and Article 90 contains general provisions and definitions—so none of these primarily govern grounding and bonding.