WCA September 2011

Reaction to fire performance of cables By Terence Journeaux, Prysmian Cables & Systems Limited, UK

Within this international framework there are, of course, differences from region to region and country to country in the way that the hazards of combustion of cables are approached and the applications for which the established test methods are referenced. The cable industry therefore provides products with a wide range of reaction to fire performance to reflect the varying end user requirements. Historical Development Much of the early work relating to improvements in the fire performance of electric cables was carried out in the 1970s and 1980s (1,2,3) . A four stage approach was taken at the time: • minimise the hazard by restricting the amount of burning and reducing the propagation of fire along cable runs • minimise the emission of smoke leading to obscuration of exits and prevention of escape • minimise the emission of acid gas leading to corrosion of equipment • minimise the emission of harmful fumes leading to incapacity or irritation and prevention of escape by people It was recognised that these factors would assume varying levels of importance according to the particular market sector and typical installation condition considered (4) .

Abstract This paper covers the European Commission decision of October 2006 implementing Council Directive 89/106/ EEC with regard to the classification of the reaction to fire performance of construction products and the steps being taken toward implementation. It reviews progress on various necessary standards for test methods, classification, products, and rules for extended application (EXAP); initial output from the Europacable-funded CEMAC II project to provide technical background for implementation; and the challenges of product development. Introduction The objective of this paper is to give an overview of the current status and possible future direction in the way that regulators, specifiers and cable manufacturers address reaction to fire performance when cables burn. Specifically, it addresses the situation in the European Union. It is not intended to provide a detailed description of the test methods used or a discussion as to their validity. The cable industry has had a long history in the development of test methods and products designed to lessen the hazards resulting from burning cables, going back to the 1960s. The industry was one of the first in the

electrotechnical sector to develop tests for the assessment of the reaction to fire performance of its products and has continued to refine and improve these methods over the years. Standards covering flame spread, heat release, opacity, corrosivity and toxicity of fire effluent are today in use and the industry continues to sponsor research into the improvement of the fire performance of its products and the definition of appropriate test methods. In the fire area, there has been a longstanding commitment to international standards through the IEC (International Electrotechnical Commission) and many national and regional standards eg EN (European Standard) are based upon the IEC publications.

❍ ❍ Figure 1 : Schematic of prEN50399 test apparatus

Extraction

Bi-directional Probe

Lamp and Photocell

Hood

Exhaust

Measurement Rack

Test Chamber IEC 60332-3-10

Cables Tested

Measure and Control of Primary Air flow

Burner

Controlled Blowing Fan

Air Inlet

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Wire & Cable ASIA – September/October 2007 11