Flammability Characteristics of Electrical Cables Using the Cone Calorimeter

摘要

Cone calorimeter tests were performed on eight multi-conductor electrical cables. Measurements of ignition delay time, heat release rate, mass loss rate, and gas and smoke generation rates were made in the vertical (2 irradiance levels) and horizontal (3 irradiance levels) orientations. It was found that comparable ignition delay times were observed for all of the cross-linked polyolefin jacketed cables. The PVC jacketed cable had a substantially lower ignition delay time. All of the cables exhibited an ignition delay time dependence on external irradiance proportional to 1/q2. Sample orientation did not significantly affect the ignition delay time. Heat release rate measurements showed that cables burned in multiple stages. Each stage of burning was associated with the decomposition of a different layer of the cable assembly. For some cables, at low external irradiances (25 kW/m2) only the outer jacket burst open exposing the interior cable materials and secondary heat release rate peaks resulted. Changes in the cable components actually burning were reflected in variations in mass loss, gas, and smoke generation rates as well as small changes in the effective heat of combustion.