National Fire Protection Association (NFPA)

The National Fire Protection Association (NFPA) is a national industry organization that creates and maintains, private, copyrighted standards and codes for fire prevention and life safety. NFPA also establishes safety and performance standards for emergency standby generator sets and transfer switches. Many local governments and critical facilities such as healthcare facilities have adopted NFPA standards for applications where failure of the emergency power supply system (EPSS) could result in loss of human life or serious injuries.

NFPA 70 – National Electric Code (NEC) – The National Electric Code has been adopted by all 50 states in order to codify the requirements for safe electrical installations into a single standard. The NEC applies to construction and installation activities and details requirements for electrical design, installation, and inspection. The NEC articles that specifically apply to backup generators and transfer switches include:

• Article 445 – Generators – Contains the installation and other requirements for generators including nameplate markings, overcurrent protection, the ampacity of conductors, and disconnecting means.

• Article 700 – Emergency Systems – Applies to the installation, operation, and maintenance of emergency systems that are legally required by a governmental Authority Having Jurisdiction (AHJ). These systems are intended to automatically supply illumination and/or power essential for safety to human life. This requirement is designed to ensure that lighting and life safety loads take priority over other building loads and that backup power is available to these loads within 10 seconds of a utility power failure.

• Article 701 – Legally Required Standby Systems – Applies to the installation, operation, and maintenance of legally required standby systems. While Article 700 is written to ensure that people can safely exit a building, Article 701 is written to aid firefighters, rescue personnel, and other first responders by requiring that standby power be available to legally required systems within 60 seconds of a power loss.

• Article 702 – Optional Standby Systems – Applies to applications where standby generators are optional, such as public or private facilities where life safety does not depend on the performance of the system. In these cases, the systems may be put in place to protect against economic loss or business interruptions. For instance, in data centers, manufacturing plants, small businesses, homes, and other applications where standby power isn’t legally required.

• Article 708 – Critical Operations Power Systems – This article was developed following the 9/11 terrorist attacks and the Hurricane Katrina disasters in the U.S. It requires critical operations power systems installed in facilities that, if destroyed or incapacitated, would disrupt national security, the economy, or public health or safety be able to support the Designated Critical Operations Area (DCOA) at full load for a minimum of 72 hours. The local AHJ has the authority to require facilities like police stations, fire stations, emergency call centers, telecommunications carriers, data centers, and other critical infrastructure applications to comply with Article 708.

NFPA 99 – Healthcare Facilities Code – The Healthcare Facilities Code is primary to the NEC in relation to performance, maintenance, and testing in healthcare facilities. It provides requirements for which loads and equipment goes on emergency circuits in various healthcare facilities and requires that healthcare facilities must exercise emergency power supply systems under load and at operating temperature for at least 30 minutes at intervals that do not exceed 30 days.

NFPA 101 – Life Safety Code – The Life Safety Code outlines requirements for emergency lighting and exit signs. It specifies which types of facilities require emergency lighting (healthcare facilities, places of assembly, correctional institutions, hotels, dormitories, apartment buildings, and certain mercantile buildings) of the means of egress and the areas where emergency lighting and signage is required, as well as the illumination requirements. The Life Safety Code refers to the NEC for the requirement for emergency systems and NFPA 110 for installation, testing, and maintenance of the generator set used to power the emergency lights and signs.

NFPA 110 – Standard for Emergency and Standby Power Systems – NFPA 110 is written specifically for emergency and standby power systems and covers installation, maintenance, operation, and testing requirements as they pertain to the performance of the emergency power supply system (EPSS). It includes standards related to generators, transfer switches, fuel systems, circuit breakers, and other components of the EPSS.

• Classification of EPSS – Chapter 4 of NFPA 110 uses Class, Type, and Level to classify an EPSS. Class indicates the minimum time in hours that the EPSS will run without refueling (e.g. Class 48 = 48 hours). Type indicates the maximum time in seconds allowed before the EPSS assumes the load. (e.g. Type 10 = 10 seconds). Level indicates the importance of the installation to life safety (e.g. Level 1 for applications where the failure of the equipment could result in loss of human life or serious injuries).

• Generator Equipment and Accessories – Chapter 5 defines specific equipment and accessory requirements for generators. It includes requirements for fuel supplies, prototype testing, block heaters, battery chargers, instruments and control panels, and other parts of the generator set and accessories.

• Transfer Switch Equipment – Chapter 6 defines specific equipment requirements for transfer switches. It includes requirements for electrical ratings, enclosure types, ATS features, and overcurrent protection.

• Installation – Chapter 7 covers installation and environmental considerations based on the location and type of application. It includes requirements for indoor and outdoor installations, design considerations for installing the equipment, and acceptance testing requirements.
• Maintenance and Testing – Chapter 8 covers routine maintenance and operational testing requirements for the EPS (i.e. generator, batteries, fuel system) and the other major components of the EPSS (i.e. transfer switches, circuit breakers, etc.) to ensure that the system is capable of assuming full-rated load within the time required for the type and for the time specified for the class. Weekly inspections and monthly testing is required for Level 1 EPSSs. Circuit breakers must be exercised annually. A Level 1 EPSS must be tested for at least four hours once every 36 months. Generators may also be required to be tested annually for two continuous hours using a load bank. ATS’s are also subject to an annual maintenance program, including one major maintenance and three quarterly inspections. All data and readings should be recorded in an on-site maintenance log for future inspection and reference.

Other standards that may apply to generator sets and on-site power systems depending on the application include:

• NFPA 20 - Centrifugal Fire Pumps
• NFPA 30 - Flammable and Combustible Liquids Code
• NFPA 37 - Stationary Combustion Engines and Gas Turbines
• NFPA 54 - National Fuel Gas Code
• NFPA 58 - Standards for Storage and Handling of LPG

To download the NFPA standards, see the NFPA website: www.nfpa.org