Burning Behaviour of Bunched Cables. IEC The European Commission and The European Cable Industry (EUROPACABLE) are finalising. Definitions. IEC refers to various definitions, together with the following during the standard: .. F – B F. Category C, designation F – 3C F. IECC describes a method of type approval testing to define the ability of bunched cables to resist fire propagation. In this test, a cable specimen.
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Fire retardant cables are designed for use in fire situations where the spread of flames along a cable route need to be retarded. Due to relative low cost, fire retardant cable s are widely used as fire survival cables. No matter the cables are installed in single wire or in bundles, during a fire, the flame spread will be retarded and 06332-3c fire will be confined to a small area, thus reducing the fire hazard due to fire propagation.
Fire resistant cables are designed to maintain circuit integrity of those vital emergency services during the fire. The fire resistant cables exhibit same performance even under fire with water spray or mechanical shock situation.
The European Electrical Committee categorized the fire performance of the cables into three classes, namely.
If a cable can pass a specified UL fire standard, an UL performance verification mark can be applied onto the cable jacket, illustrating both the UL class and the number. There are four primary fire testing standards as follows:. Plenum rated cables meet the NFPA standard formerly known as UL which provides the most stringent requirement of all the tests.
Cable samples on a horizontal tray in a tunnel type of chamber are burned at To qualify for a plenum rating, the cables must have the flame spread of less than 5 feet or 1. Riser rated cables meets UL Cable samples on a vertical shaft are burned at To qualify for a riser rating, the cables must have the flame spread of less than 12 feet beyond the ignition point. This test does not look at the smoke density or toxicity.
Burning Behaviour of Bunched Cables
Riser cable is suitable for vertical shafts not defined as an environmental air plenum. General purpose cables meets UL The cable is deemed to pass the test if the flame spread will not extend to the upper portion and extinguish by itself.
The CMG cables are usually used in runs penetrating single floor. This cable cannot be installed in vertical pathways. The restricted cable meets ULLimited-use. The test consists of 25 feet long ventilated tunnel. The CMG cable is suitable for use in.
This cable cannot be installed in bundles and must be protected in metal conduit. This type of cable is the minimum requirement in commercial installations. This is a test for assessing the performance of a material when it is tested in accordance with BS Method A and B. The oxygen index of a material will drop when the temperature rises. This temperature is defined as temperature index. The temperature index of the coal is defined as C. In general, the temperature index of fire retardant cable exceeds C.
This is a test defined by Naval Engineering Standard which is a directed at the analysis of a specified set of gaseous species which are commonly present in the combustion products of materials used in military application and which may cause lethality at the time of a fire.
In this test, a 1 g cable specimen are completely burnt inside a sealed chambers of volume 0. The resulting chamber atmosphere is quantitatively analysed for a specified set of gases.
For each gas, the measured concentration Ci is scaled up for g and the concentration is recalculated as though the combustion products is diffused into a volume of exactly 1m3.
The resulting concentration C8 is expressed as the ratio of critical factor Cf which is equal to the concentration of this gas considered fatal to human for 30 minutes exposure. The higher the toxicity index, the more toxic the cable material is.
System 6 UTP LSOH Cable (IEC 60332-3C) – International
In general, the toxicity index of LSZH material is less than 5. Thus, LSZH cable cannot be categorized as toxic free. Fire resistant cables are designed for maintaining circuit integrity during a fire. Comparitively speaking, the fire performance requirement for BS is more demanding. IEC details a method of test for assessing the fire resisting characteristics of a cable. The cable is defined as fire resisting ifunder the conditions of this test, it being assumed that the test flame intensity is of sufficient magnitude to destroy the organic material, no failure of any of the 3A fuses occurs and if the withstand voltage on completion is not less than the rated voltage of the cable.
The cable sample is deemed to pass this test if no fuse was ruptured nor any lamps extinguished during the 3 hour flame application and on re energizing the cable after 16 hours. BS specifies the performance requirements for cables required to maintain circuit integrity under fire conditions. It details the following methods to categorize the cables according to cable withstand capacities. Resistance to fire alone — the cables is tested by gas burner flame while passing a current at its rate voltage.
Four survival categories are defined: Resistance to fire with water spray — a new sample of cable is exposed to flame at C for 15 minutes while passing a current at its rated voltage and then the spray is turned on to give exposure to both fire and water for a further 15 minutes.
A single survival category W is defined if the cables surpassed the testing requirement. Resistance to fire with mechanical shock — the final requirement is mechanical shock damage. A fresh sample is mounted on a backing panel in a S bend and is exposed flames while the backing panel is stuck with a steel bar with same diameter as the cable under test every 30 seconds for 15 minutes. The cables will be tested under the following temperatures: Home Product Dispaly Navigation.
LSZH cables are not only characterized by its fire retardant performance but also by its halogen free properties, thus offering low corrosivity and toxicity. During a fire, this cable will emit less smoke and acid gases which may damage the human being and expensive equipment.
Compared with normal PVC cable, LSZH cable outperforms by its fire retardant properties, low corrosivity and low smoke emission properties, however, normal PVC cables has better mechanical and electrical properties. The lowhalogen content and low corrosivity of low smoke fume cables lies somewhat in between fire retardant cable s and LSZH cables.
Low Halogen cable also contains halogen but the content is much less than PVC cables. LSF cable is designed to reduce the spread of fire, toxic gases and smoke during fire. These materials help improve the fire performance of the LSF cables. The main concern for the cable in its fire survival properties are its flame spread, smoke characterization and and gas toxicity.
In American fire standard, the concern lies more on the first two and it differs from the European standard which concerns all these aspects. Therefore, to control the heat release is the most important concern for reducing the fire hazard.
However, in European countries, halogen content, the corrosivity of the gases, the smoke density and the toxicity of the gas are equally important factors affecting the safety and survival of human during a fire. IEC and IEC are used to assess the flame propagation characteristics of a single wire.
Reduced Fire Propagation in accordance with IEC |FAQ
IEC is used to assess the flame propagation chacteristics of bundled cables. This test details a method of test for the assessment of the flame propagation characteristics of a single wire or cable. In this testa 60cm cable sample is fixed vertically inside a metallic box and a mm long flame is applied at 45C from a gas burner placed at mm from the top at the upper portion. The specimen is deemed to have passed this test, of after burning has ceased, the charred or affected position does not reach within 50mm of the lower edge of the top clamp which is equivalent to mm above the point of flame application.
The test method is not suitable for the testing of some small wires due to the melting of the conductors during the time of application of the flame. IECC describes a method of type approval testing to define the ability of bunched cables to resist fire propagation. In this test, a cable specimen, consisting of number of 3. The cable specimen is deemed to have met the requirements of the standard if, after burning has ceased, the extent of charred or affected portion does not reach a height exceeding 2.
This general purpose cables also meets UL This specifies a test for determination of the amount of halogen acid gas, other than the hydrofluoric acidevolve d during combustion of compound based on halogenated polymers and compounds containing halogenated additives taken from cable constructions. All these elements are toxic by its nature. In this test, when the burner is heated to C, 1g sample is placed inside and the HCL is absorbed into water inside the chamber fed with air flow.
The water is then tested with its acidity. To determine if the cable is halogen free, IEC should be used. This test specifies a method for the determination of degree of acidity of gases evolved during combustion of cables taken from the cable sample by measuring its pH and conductivity.
The specimen is deemed to pass this test if the pH value is not less than 4. This specifies a test for determination of smoke density. A light beam emitted from a window is projected across the enclosure to a photo cell connected to a recorder at the opposite window. A 1 metre cable sample is placed in the centre of the enclosure and is applied with a fire. The minimum light transmission is recorded.
The result is expressed as percentage of light transmitted. The higher the light transmittance, the less smoke emitted during a fire. At room temperature, when the oxygen content in the air exceeds the oxygen index, the material will burn by itself automatically.
System 6 UTP LSOH Cable (IEC C) – International
The higher the oxygen index, the more retardant the cable is. Real Time Patching System. Addison Fire Resistant Cable. There are four primary fire testing standards as follows: IEC fire performance standard. BS BS specifies the performance requirements for cables required to maintain circuit integrity under fire conditions.