Which NEC article covers emergency systems?

• A. Article 480
• B. Article 517
• C. Article 701
• D. Article 700

Answer: (D)

Emergency power systems are designed to keep life-safety loads powered during a loss of normal power, and the NEC addresses them specifically in a single article titled Emergency Systems. This article covers how emergency sources (such as generators or stored-energy systems) connect to life-safety equipment, how those sources are coordinated with normal power (including automatic transfer switches), and the rules for wiring methods, protection, testing, and maintenance to ensure reliable operation when the utility power fails.

The other topics are different kinds of standby or storage arrangements and have their own sections. Legally required standby systems pertain to power for certain operations required by law or codes, while optional standby systems cover selected loads that are not mandated but may be supplied by an auxiliary source. Storage batteries focus on energy storage devices themselves rather than the broad emergency distribution system. So the article specifically dedicated to emergency systems is the one that governs this concept.