Which article of the NEC requires that any electrically conductive materials that are likely to become energized shall be bonded and grounded at the point of entrance into a building?

Article 250 of the National Electrical Code (NEC) focuses on grounding and bonding requirements. This article is crucial because it mandates that any electrically conductive materials that might become energized must be properly bonded and grounded to minimize the risk of electric shock or fire hazards. Specifically, it outlines the methods and techniques for ensuring that these conductive materials are effectively connected to the grounding system of the building when they enter.

The bonding process helps create a low-resistance path that allows fault currents to flow safely to the ground, protecting both the building's electrical system and its occupants. This is particularly important for maintaining safety in installations involving various conductive materials, such as metal enclosures and raceways, where there's a potential risk of electrical faults.

In contrast, the other articles mentioned cover different aspects of electrical installations. Article 770 deals with optical fiber cables and their installation, Article 568 pertains to specialty occupancies like modular buildings, and Article 300 outlines general installation requirements for wiring methods. While they are important for their respective topics, they do not specifically address the bonding and grounding requirements for conductive materials entering a building as Article 250 does.