EoW July 2011

technical article

References

the emission of the most important corrosive and irritant gases still remain valid today although refinement and improvement in methodologies have been achieved in the intervening years. The advent of new requirements based on integrated tests involving heat release has been, and will continue to be, a major challenge particularly in Europe. The effects of the new European regulatory framework for the classification of a cable’s reaction to fire performance will be a major change from the existing voluntary position. Just how the European classification and CE Marking of fire performance under the CPD will affect the cable market is difficult to predict. Implementation is strictly a National matter and whilst it is known that some countries that do not now regulate for the reaction to fire performance of cables have no intention of regulating in the future, other countries have indicated an intention to use the classification in regulation. However, which Euroclass is specified for any particular application is again a national matter. At a European level, it is likely that the cable industry will continue to be required to supply many different levels of performance, although in time we may expect to see users moving towards the higher classes as cost effective cable designs become available. Comparison of prEN50399 tests with results from existing IEC tests is difficult due to the different conditions selected for the tests and the multi-criteria approach of the classification. Experience gained from the CEMAC II project has shown that prEN50399 results are in general greatly influenced by cable size – the smaller the cable, the more onerous the test. Results for larger power cables (conductor sizes greater than 35mm 2 ) can generally be predicted from IEC60332-3-24 (Category C) test results as the mounting in each test is similar but no such relationship exists for smaller cables due mainly to the totally different mounting in each test. Recent work has demonstrated that real time measurement of effluent in a large scale fire test (such as prEN50399) is possible and that such results can be used as input into modelling studies. However, it is clear that further work would be necessary before any standardisation could take place. Through its ongoing and demonstrated ability to invest in research, the cable industry will be in a good position to meet the challenges resulting from any new regulatory or end user demands on the fire performance of its products. n

1 Zanelli, C, Philbrick, S, Beretta, G, “Cavi e pericolo di incendio”Cired, London 1973 2 Philbrick, S, McConnell, J,“Cables having improved fire performance”Jicable 84, Versailles 1984 3 Journeaux, T, Beratta, G, Gautier, P, “Development of cables with improved fire performance characteristics”Jicable 87, Versailles 1987 4 Journeaux, T, “The development of new standards for offshore cabling” PRI Conference Polymers for Offshore Cabling Proceedings, London 1987 5 IEC Standard IEC 60332-3-10:2000 + A1:2008 Tests on electric cables under fire conditions – Part 3-10: Test for vertical flame spread of vertically mounted bunched wires or cables – Apparatus 6 IEC Standard IEC 60754-1:1994 Test on gases evolved during combustion of materials from cables – Part 1: Determination of the amount of halogen acid gas 7 IEC Standard IEC 60754-2:1997 Test on gases evolved during combustion of electric cables – Part 2: Determination of degree of acidity of gases evolved during the combustion of materials taken from electric cables by measuring pH and conductivity 8 IEC Standard IEC 61034-2:2005 Measurement of smoke density of cables burning under defined conditions – Part 2: Test procedure and requirements 9 Gibbons, J, Stevens, G, “Limiting the corrosion hazard from electrical cables involved in fires” Fire Safety Journal 15 p183-190, 1989 10 Telecom Australia, Design standards Branch, HQ Fire loss report, 1987 11 Stevens, G, “The appraisal and significance of acidic gas emissions from burning electric cable materials,” 5 th BEAMA International Electrical Insulation Conference, Brighton 1986 12 Journeaux, T, “The development and manufacture of Sizewell B cables,” Proceedings IEE International Conference on control aspects of the Sizewell B PWR, p74-79 London 1992 13 Hull, T, Stec, A, Paul, K, “Hydrogen Chloride in Fires,” IAFSS 9 th International symposium, Karlsruhe 2008 14 Hertzberg, T, Blomqvist, P, Lastbom, L, “Influence of HCl and PVC-smoke on isolated and perfused guinea pig lungs,” SP Fire Technology Report 57, 2006 15 Journeaux, T, “Development in regulatory classifi- cation methods that will affect the European cable industry and its suppliers,” Flame Retardants 2008, Interscience Communications Ltd, London 16 Draft prEN 50399 Common test methods for cables under fire conditions – Heat release and smoke production measurement on cables during flame spread test – Test apparatus, procedures, results, CLC TC20/Sec1577/INF June 2008 17 European Commission, Mandate to CEN and CENELEC concerning the execution of standardisation work for harmonised standards on power, control and communication cables M/443, Brussels, 18 th May 2009 18 Johansson, P, Blomquist, P, Sundstrom, B, “Feasibility study of supplementary FTIR measurements in tests with electric cables according to Commission Decision 2006/751/EC, FIPEC20Scen1 (prEN50399),” Safety during fire, Europacable, Brussels 2009 19 Messa, S, “Investigation into the smoke effluents of burning cables,” Safety during fire, Europacable, Brussels 2009 20 Van Hees, P, Nilsson, D, “Simulation of critical evacuation conditions for fire scenario involving cables and comparison of different cables,” Safety during fire, Europacable, Brussels 2009

Prysmian Cables & Systems Ltd – UK Email : cables.marketing.uk@prysmian.com Fax : +44 238 0295 335 Website : www.prysmian.com

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EuroWire – July 2011