Tests show faster flame spread in cables when they are pre-heated. Tested HFFR cables performed better than PVC cables. All the cables were IEC 60332-1-2 fire rated and the HFFR (halogen-free flame retardant (PEVA/PE based) cable was additionally IEC 60332-3-23 fire rated. Several cables were placed on a metal grid cable tray, total 3.4 m long (CISCCO test rig). Flame spread was faster in the PVC cables (up to 5.5 m/s) than in the HFFR cables (up to 1.5 mm/s), with flame spread rate increasing significantly in the PVC cables from around 170-250°C after pre-heating, but only from around 280-370°C with the HFFR cables. Fire growth rate was also related to pre-heating temperature, and was linearly correlated to flame spread rate.
“Flame Spread Experiments on a Horizontal Preheated Cable Layer”, PL Zavaleta et al., Fire Technology, 60, 641–667, 2024 https://doi.org/10.1007/s10694-023-01521-5.