8 - Flammability tests for cables

Abstract

A fire in a cable installation can lead to substantial damage in different ways. The burning cables will stop functioning. A cable ladder full of cables can burn at a very high intensity. Depending on the type of cable, polymers, and flame retardants involved, large amounts of smoke and toxic gases can be produced. Most of the international standardization in the electrical area takes places inside the International Electrotechnical Commission (IEC). IEC produces fire standards for all sorts of electrical equipment. Cables are handled in the IEC/TC20 committee. Tests of wide use are the vertical small flame test, IEC 60332-1, for a single insulated cable and the large-scale vertical cable ladder test, IEC 60332-3. The two tests are well established and are also found in many national regulations. IEC 60332-1 measures the tendency for a single cable to be ignited and spread flames when exposed to a small Bunsen burner flame, comparable to a candle-like ignition. In IEC 60332-3 cables mounted on a vertical ladder are exposed to flames from a gas burner giving approximately 20kW. The International Standardization Organization (ISO) TC 92 Fire Safety Committee is developing test methods for measurement of the heat release rate, ignitability, flame spread, smoke production and production of gas species from all sorts of products exposed to fire. In addition toxicity of fire gases is evaluated and tools for fire safety engineering are standardized. These tests and techniques are also applicable to cables.