Scholarly record

INFORMATIVE VALUE OF ELECTRICAL CABLE REACTION TO FIRE CLASS

Jozef Martinka

Abstract

Electrical cables are one of the key components of green building technologies. They are crucial for the operating of many green building technologies (e.g. power transfer from the solar cell to other building electric devices). For fire safety level assessment of electrical cables installed in green buildings are used their fire characteristics. The reaction to fire is the fundamental and most important fire characteristic of electrical cables. Nevertheless, it is used almost exclusively in the prescriptive approach to fire safety of structures (in the prescriptive approach, the law or technical regulation specifies the minimum class of reaction to fire of electrical cables in certain areas, e.g. escape routes). However, the actual contribution of an electrical cable to the development of a fire and a decrease in visibility in a fire compartment is not obvious from the reaction to fire class. In this paper considered fire scenario is selected: the amount of released heat and the loss in visibility in the fire compartment caused by the fire of electric cables (15 mm in diameter) classified as fire B1ca, B2ca and Cca reaction to fire classes and additional classifications for smoke s1 and s2. Space used in the considered fire scenario have 20 x 10 x 8 m, in which 5 (unprotected) electric cables were installed side by side under the ceiling. Six cases were analysed under same conditions of fire scenario (class B1ca - s1, B1ca - s2, B2ca - s1, B2ca - s2, Cca - s1, Cca - s2). In each case analysed, all 5 electrical cables had the same class of reaction to fire and the cables were ignited by Joule heat. Three values of the total amount of released heat and smoke extinction area were investigated for each case. The first was value (released heat and smoke) investigated was the most favourable (minimum), the second least favourable (maximum), and the third mean value, which still allow the cable to be classified into the appropriate fire reaction class (or additional classification). The data obtained show that there are also significant differences between the cables with the same fire reaction class (or additional classification) in terms of heat released and loss of visibility in the fire compartment, during fire.

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DOI resolver: doi.org/10.5593/sgem2019v/6.3/s09.040

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