Which NEC article focuses on Overcurrent protection: sizing and protecting conductors and devices to prevent overheating?

• A. Article 250: Grounding and bonding to establish a safe path to earth and equalize potential.
• B. Article 300: General wiring methods and the installation of conductors, cables, raceways, and enclosures.
• C. Article 240: Overcurrent protection: sizing and protecting conductors and devices to prevent overheating.
• D. Article 310: Conductors for general use: ampacity, insulation, and temperature ratings.

Answer: (C)

Overcurrent protection is addressed by NEC Article 240, which lays out how to size and protect conductors and devices to prevent overheating. It specifies the selection and protection of overcurrent devices (fuses and circuit breakers) and ties the protection to conductor ampacity to ensure wires aren’t heated beyond their ratings. The goal is to interrupt current before insulation can be damaged or a fire can start, whether the overload comes from normal overcurrent or a fault.

In practical terms, Article 240 ensures you choose the right device rating for the circuit and that the conductors feeding the circuit are protected appropriately, typically by aligning the OCPD rating with what the conductors can safely carry as determined by Article 310. The protection must also be suitable for the potential fault current and the equipment’s interrupting capacity.

Other options cover different topics: grounding and bonding (establishing a safe path to earth), general wiring methods (how conductors, cables, raceways, and enclosures are installed), and conductors for general use (ampacity, insulation, and temperature ratings). These areas are not focused on overcurrent protection.