Understanding NEC Article 700: Emergency Systems

NEC Article 700 provides critical guidelines for the installation, operation, and maintenance of emergency systems. These systems are designed to supply power and lighting to essential facilities during normal power outages, ensuring safety and functionality in high-stakes environments such as assembly areas, hospitals, and industrial sites.

Scope of Article 700

This article applies to:

• Emergency systems delivering electricity for illumination, power, or both in required facilities when the normal electrical supply fails.
• Facilities like theaters, sports arenas, healthcare institutions, and areas where failure of power poses life safety risks.

Referenced Standards:

• NFPA 101: Life Safety Code.
• NFPA 110: Standard for Emergency and Standby Power Systems.
• NFPA 111: Standard on Stored Electrical Energy Emergency and Standby Power Systems​.

Key Requirements for Emergency Systems

1. General Requirements (700.1)
   • Emergency systems must provide power for functions like safe exiting, fire detection, communication systems, and life support where needed.
   • Systems must comply with local, state, or federal codes.
2. Maintenance and Testing (700.3)
   • Systems must undergo periodic testing and commissioning to ensure readiness.
   • Records of tests and maintenance are required.
   • Temporary power must be provided during maintenance of the emergency source​.
3. Capacity and Coordination (700.4)
   • Systems must handle full load requirements, including transient power conditions.
   • Selective load management ensures emergency loads are prioritized over optional standby systems.
4. Transfer Equipment (700.5)
   • Automatic transfer switches (ATS) must prevent unintentional interconnection of power sources and meet reliability standards.
   • Redundant systems may be required for critical facilities​.
5. Wiring Requirements (700.10)
   • Emergency circuits must remain independent of other wiring unless explicitly permitted.
   • Fire-rated installations are mandatory in specific high-risk buildings.
6. Sources of Power (700.12)
   • Emergency power must activate within 10 seconds of failure and be sustained for at least 2 hours, unless otherwise specified.
   • Acceptable sources include generators, storage batteries, uninterruptible power supplies (UPS), and microgrids.

Control and Safety Features

1. Surge Protection (700.8)
   • Emergency switchgear, panelboards, and related equipment require surge protection to maintain system integrity.
2. Control Devices (700.23–700.26)
   • Controls for dimmers, automatic load relays, and directly controlled emergency luminaires must be listed for emergency use.
3. Lighting and Power Circuits (700.17–700.19)
   • Emergency lighting must activate automatically upon power failure, preventing areas from being left in darkness.
4. Selective Coordination (700.32)
   • Overcurrent protection must be designed to localize faults without disrupting critical emergency loads​.

Applications

NEC Article 700 applies to installations in:

• Public Spaces: Large venues, malls, and assembly areas.
• Healthcare Facilities: Hospitals and clinics requiring uninterrupted power for life-support equipment.
• Industrial Settings: Sites where power failure could lead to safety or environmental hazards.

Conclusion

NEC Article 700 ensures the functionality and safety of emergency power systems by setting rigorous standards for installation, operation, and maintenance. These systems are vital in protecting human life and maintaining critical operations during power interruptions.