NEC Article 700 provides comprehensive requirements for the installation, operation, and maintenance of emergency systems. These systems are critical for ensuring safety during power outages by providing backup power to essential circuits and equipment. Here is a detailed overview of the key sections within this article:
700.1 Scope
This section outlines the scope of Article 700, covering emergency systems that are intended to supply, distribute, and control electricity for illumination, power, or both during an emergency when the normal electrical supply is interrupted.
700.2 Definitions
Defines essential terms related to emergency systems, including “emergency systems,” “legally required standby systems,” and “optional standby systems,” ensuring clarity and consistency in application.
700.3 Tests and Maintenance
Mandates regular testing and maintenance of emergency systems to ensure they remain operational during an emergency. This includes requirements for periodic testing, record keeping, and ensuring systems are kept in proper working condition.
700.4 Capacity and Rating
Specifies that emergency systems must have adequate capacity to carry the full emergency load. The system must be capable of handling the entire emergency load at any one time, including motor startup currents. This ensures that essential systems remain operational during an emergency.
700.5 Transfer Equipment
Details the requirements for transfer equipment, which must automatically transfer the load to the emergency power source in the event of a normal power failure. Meter-mounted transfer switches are not permitted for emergency systems.
700.10 Wiring
Requires that wiring for emergency systems be kept entirely independent of all other wiring and equipment. This separation minimizes the risk of failure due to faults in non-emergency systems and ensures reliability.
700.11 Circuit Wiring for Emergency Lighting Systems
Specifies the acceptable wiring methods for emergency lighting systems. This includes the use of Class 2 circuits for certain emergency lighting systems utilizing low-power technologies such as Power over Ethernet (PoE).
700.12 Power Sources
Outlines the acceptable power sources for emergency systems, including storage batteries, generator sets, uninterruptible power supplies (UPS), and other approved sources. These sources must be capable of supplying the emergency load for a specified duration, typically not less than two hours.
700.16 Emergency Illumination
Mandates that emergency lighting systems provide illumination for safe egress and other critical functions during a power outage. This section includes requirements for the location and performance of emergency lighting fixtures.
700.32 Selective Coordination
Requires that overcurrent protective devices for emergency systems be selectively coordinated with all supply-side overcurrent protective devices to ensure that a fault in one circuit does not affect the entire emergency system.
By adhering to these detailed requirements, NEC Article 700 ensures that emergency systems are designed, installed, and maintained to provide reliable backup power during critical times. For further detailed information and specific requirements, consulting the NEC Handbook and additional resources provided by the NFPA is highly recommended.