The effects causing the burning of plastic coatings of fire-resistant cables and its consequences

Abstract

"Electric wiring is part of the fire protection systems"," therefore, it must work reliably for a given period of time. Cable is inthe first place among the cause of fire. Fires are always triggered by unsafe and nonstandard conditions, so we can approachsafety if we know the properties of cables we want to use. We recommend adding standard ratings (PH, EP) with overloadand combustion in increased/higher oxygen ratio. A plastic-coated cable does not burn in normal air, but, in a higheroxygen ratio, it shows specific burning phenomena. Cable fires may have two starting points: One is the heat reaching theplastic insulation of cables, due to the fire created by burning"," the other one may be due to the fire generated by theovervoltage in the inappropriately sized cables when the outer plastic coating begins to burn. The basic condition of fireretardancy is that wire breaks or short circuits may not occur in a cable system. During this research, both effects are testedon fire-retardant cables. On the one hand, we exposed wires of various plastic sheaths to flame and to heat, as well as testedat which actual oxygen content they start combustion and flame propagation. In addition, we have investigated how fire-resistant cables react to a possible overvoltage when auto-ignition occurs. The goal was to see how conventional testsreflect requirements caused by a real fire and what the actual fire resistance of cables is, as well as examining whether thecables that have been certified as fire-resistant meet the requirements under real fire. The limited oxygen index (LOI)parameter seemed to be the most appropriate for real fire resistance. Our results have shown that factory certifications arenot enough to provide complete fire safety. For example, the PH 180, E90 best rated plastic gave the weakest LOI value.PH 30 and PH 120 has proved correct the flammability. Due to the complex layers their investigation their testing iscomplex to, requiring a variety of tests to give a complete burn behavior. The most important exothermic peaks ofdiagraphs give the expected LOI values. The first and second decomposition is only indicative of damage and smoke, thatis only by the tests with overload to see."

Electric wiring is part of the fire protection systems, therefore, it must work reliably for a given period of time. Cable is inthe first place among the cause of fire. Fires are always triggered by unsafe and nonstandard conditions, so we can approachsafety if we know the properties of cables we want to use. We recommend adding standard ratings (PH, EP) with overloadand combustion in increased/higher oxygen ratio. A plastic-coated cable does not burn in normal air, but, in a higheroxygen ratio, it shows specific burning phenomena. Cable fires may have two starting points: One is the heat reaching theplastic insulation of cables, due to the fire created by burning, the other one may be due to the fire generated by theovervoltage in the inappropriately sized cables when the outer plastic coating begins to burn. The basic condition of fireretardancy is that wire breaks or short circuits may not occur in a cable system. During this research, both effects are testedon fire-retardant cables. On the one hand, we exposed wires of various plastic sheaths to flame and to heat, as well as testedat which actual oxygen content they start combustion and flame propagation. In addition, we have investigated how fire-resistant cables react to a possible overvoltage when auto-ignition occurs. The goal was to see how conventional testsreflect requirements caused by a real fire and what the actual fire resistance of cables is, as well as examining whether thecables that have been certified as fire-resistant meet the requirements under real fire. The limited oxygen index (LOI)parameter seemed to be the most appropriate for real fire resistance. Our results have shown that factory certifications arenot enough to provide complete fire safety. For example, the PH 180, E90 best rated plastic gave the weakest LOI value.PH 30 and PH 120 has proved correct the flammability. Due to the complex layers their investigation their testing iscomplex to, requiring a variety of tests to give a complete burn behavior. The most important exothermic peaks ofdiagraphs give the expected LOI values. The first and second decomposition is only indicative of damage and smoke, thatis only by the tests with overload to see.