3. Fire resistance of cables

3.1 Old French system

Standard NF C32-070 lays down the principles for classifying conductors and cables in terms of fire behavior. The CR1 classification is awarded to cables capable of maintaining their functions for a certain period of time when exposed to fire. To obtain this classification, cables in the CR1-C1 category must demonstrate limited flame propagation, continue to operate under simulated fire conditions in a tube furnace, with temperatures following the standardized temperature-time curve, and undergo mechanical shocks while being maintained under electrical voltage...