Which NEC article covers legally required standby systems?

• A. Article 517
• B. Article 700
• C. Article 701
• D. Article 430

Answer: (C)

Legally required standby systems are the backup power category that a building must have to keep certain safety-critical loads energized during a power outage, as required by law or the authority having jurisdiction. The NEC designates this specific topic in Article 701, which lays out the rules for sizing, sources, transfer equipment, wiring, operation, and testing of systems that must remain energized when normal power is lost. This is distinct from emergency systems, which are focused on life-safety loads with automatic transfer (Article 700), and from optional standby systems, which cover backup power for loads the owner chooses to support beyond what is legally required (Article 702). So Article 701 is the one that directly covers legally required standby systems.