Traditionally Plenum rated cables are made using halogenated polymers because they tend to have excellent flame resistance. The cable has a design that ensures operation for more than 3 hours in fi es up to 1000 °C. "OF" refers to optical fiber, "N" means non-conductive, "C" means conductive, while"P", "R", and "G" stand for Plenum, Riser, and. The National Electrical Code (NEC) has classification system for optical fiber cables. These requirements specify how the fiber cables will perform under fire conditions. Choosing cables with the right Euroclass rating, like B2ca, gives. Article 770 of the National Electrical Code distinctly recognizes that General Purpose, Riser and Plenum spaces must have suitably fire rated cables, and regulates the industry with UL test specifications. This particular kind of jacket fabric offers great fire safety properties, including minimal smoke production, low toxicity, and low corrosion.