Comparative thermal decomposition characteristics and fire behaviors of commercial cables

The decomposition and fire behaviors of two commonly used cables were studied by a calorimeter. The effects of the cable type, the incident heat flux, and the thermal aging on the fire characteristics were specially analyzed. Two cables showed almost the same ignition property considering the same sheath material, and the thermally thick model for both cables was identified. The changes in mass and heat release between two cables presented a significant difference. This was ascribed to the different compositions and the structures of the cables. The theoretical derivation and experimental data fitting indicated that two cables gave a different fire risk. The fire hazard was greatly promoted under higher incident heat flux because more combustible compositions decomposed contributed to heat release. The ignition time of two cables first changed slowly with the thermal aging degree and then increased sharply, with a critical aging time of 30 days. The changing trends of mass and heat release with the thermal aging degree between two cables were significantly different, which was attributed to the different compositions of cable insulation, resulting in the different thermal aging mechanisms. This work may provide an in-depth understanding of fire behaviors of commercial cables.