Current European national fire assessment techniques are not sensitive enough to differentiate between cables with reasonable fire properties and those with very good properties needed for high hazard installations or for high density telecommunications installations. A new method for measuring the fire performance of electric cables based on sound engineering principles rather than prescriptive tests was needed to help facilitate good measurement techniques and the introduction of fire engineering in this field.
The scientific and technical objectives of this programme were to:
1. Develop or modify fire test methods for electrical cables offering improvements on existing IEC test methods so that: existing classification systems can be maintained new classifications are based on scientifically sound measurement techniques rather than prescriptive methods; the sensitivity of measurement is enhanced, to allow for subdivisions in any classification, especially at the better fire performance levels
2. Develop cone calorimeter test for small-scale testing of electrical cables
3. Develop correlation models for prediction of fire performance of cables
4. Develop bases for calculation models for prediction of cable fire performance
5. Investigate the validity of models.
Test procedures have been developed and draft standard guidance documents written and made available to the EC, national standardisation groups and CEN/CENELEC. The techniques used, which include heat release measurement, have been developed for use with existing IEC test methods to provide a more comprehensive assessment system. This increases the test sensitivity and hence service a wider range of fire performance levels than current methods. Results of the full-scale test procedures are highly repeatable and reproducible, can be used as a basis for classification and have proved to correlate well with both horizontal and vertical real scale scenario cable tests.
Test data from almost 2000 experiments are held in a database. Highly repeatable and reproducible Cone calorimeter testing protocols have been developed both to measure the heat release and smoke release properties of cables and the materials from which they are made. This resulted in a number of correlation formulae, numerical flame spread models and advanced CFD (computational fluid dynamics) modelling. The latter will allow cable fires in more complex situations to be predicted in the future and it is proposed that further efforts are made in this area. Also a first approach to a composite model based on a physical pyrolysis model has been performed. This composite model allows the prediction of the fire behaviour of the cable in the cone calorimeter by means of test results of the different materials used in the cable construction.
The FIPEC work programme comprised of the development of the fire test procedures and investigation of mathematical fire models to predict fire development in real scale scenarios from smaller scale experiments. It included a review of European cable installations, experiments on electric cables and the materials from which they are constructed. The experimental work has being carried out using specimens that represent a wide spectrum of fire behaviour and this was undertaken at different scales and linked by correlation and fire modelling studies, which are the scientific foundation for assessment.
Funding SchemeCSC - Cost-sharing contracts
SE13 5DF London
501 15 Boraas