RATE OF HEAT RELEASE TESTING FOR VINYL WIRE AND CABLE MATERIALS WITH REDUCED FLAMMABILITY AND SMOKE - FULL-SCALE CABLE TRAY TESTS AND SMALL-SCALE TESTS

Various cables were prepared with vinyl compounds, and their fire performance tested in full-scale modified cable tray tests and in a small-scale RHR calorimeter test (cone calorimeter). The cables passed all full-scale tests, except for two THHN cables (including a nylon film), made with a traditional jacket compound and not flame retarded. Information obtained from the cable tray tests included heat release, smoke release, mass loss and gas release (CO, CO2 and HCl). The smoke obscuration from the full-scale burns was heavily dependent on the extent of burning of the cables. Those cables that did not burn extensively released very little smoke. Similarly those same cables released very low amounts of combustion gases, notably HCl. Results of cone calorimeter tests on cables were well correlated with full-scale test results, both in terms of heat and smoke release. This was particularly true for the cone used at a 20 kW/m2 flux. In terms of smoke release, the total smoke released in full scale correlates well with smoke factor in small scale. Total smoke released in small scale is a much less reliable measure of full-scale smoke release than smoke factor. All vinyl compounds used to make the cables were also tested in the cone and in the OSU calorimeter. Correlations were also made of properties between both calorimeters, and were found to be excellent. Some fire properties of the jacket compound alone, in the cone calorimeter, at 20 kW/m2, can be used to give an indication of likely cable performance in a full-scale test. The best properties to be used are peak rate of heat release and smoke factor. The OSU calorimeter is less reliable as a small-scale predictor, based on jacket results only. The experimental vinyl wire and cable compounds developed show excellent fire performance in small-scale tests and show excellent fire performance when made into experimental cables.