Ignition and Charring of PVC-Based Electric Cables

The ignition of four different PVC-based electric cables was studied using cone calorimeter and the influence of the charring phenomenon on ignition was investigated. The thermophysical and optical properties of the sheaths before decomposition were measured. The kinetics of charring was studied by photogrammetry. It was shown that charring occurs for three cables before ignition at heat flux lower than 45 kW/m2. The lower is the heat flux, the higher is the char amount at ignition. In spite of the char formation, it was observed that the time-to-ignition of the cables can be properly calculated using the well-known Quintiere’s equation, considering an apparent temperature of ignition. This apparent temperature at ignition was found in the range 312°C to 349°C for the four electric cables.