In 1897, the NFPA published the world’s first National Electrical Code (NEC) to also standardize electrical safety for wiring, alarms, and related equipment. Since then, fire safety and electrical codes and standards have been adopted worldwide and have continuously evolved to help ensure best methods and practices for designing buildings.
One area of primary importance in building design is the protection of critical electrical circuits such as alarms, emergency lighting, electrical fire pump feeds, emergency generators and air handlers as well as electrical feeds for emergency elevators. Architects and engineers have a multitude of ways to design and construct such critical circuits. With over 100 years of history, codes and standards have been put to the test many times. As building designs, materials and construction methods have evolved, so too have the codes and standards.
How Fire Safety Standards Have Evolved
Over the last three decades, many code requirements have moved from 1 hour to 2 hour survivability. As buildings have become larger, taller and more complex, two hour protection is necessary to extend much needed response and evacuation time. A 2-hour fire-resistance rating is required depending on national and local codes, the type of circuit, and the environment to ensure that emergency response systems will be provided with electrical power for the required period.
However, there was one noticeable exception to this trend towards two hour protection. For many years codes continued to allow 2” of concrete encasement of standard building wire as an acceptable solution even though it was fairly well known that 2” provided only 1 hour of protection.
However, in 2018 The NFPA brought this anomaly to light when they published their technical note Fire resistance of concrete for electrical conductors which definitively concluded that 5” of concrete was required to assure 2 hours of protection. 5” of concrete is now required and incorporated into code with the release of the 2026 National Electric Code.
Preparing for the Next Generation of NEC Requirements
To learn more about the evolution of fire safety and electrical codes as they apply to critical circuits and the pros and cons of different code approved solutions, please visit our website where you will be able to download our detailed white paper on this subject; Protecting Critical Building Circuits from Fire.
