Impact of the electric cables installation on the ignition parameters of the spruce wood surface

This study is aimed to investigate of an impact of electrical cables installed on Norway spruce (Picea abies (L.) Karst.) wood board surface on main ignition parameters (mainly critical heat flux, ignition temperature, thermal response parameter and thermal inertia). Ignition parameters have been determined by dependence of ignition times (raised to the power of -1, -1/2 and -0.547) on heat flux. Initiation times have been measured for three configurations of spruce wood boards with surface dimensions of 100 x 100 mm ± 1 mm (the first configuration: board without cables on surface, the second configuration: board with three electrical cables on surface – spacing between cables was equal to their diameter and the third configuration: board with five electrical cables – spacing between cables was equal to their diameter) at five heat fluxes (30, 35, 40, 45 and 50 kW·m-2). Obtained results proved that installation of the electrical cables on the spruce wood board surface has a significant impact on the ignition parameters. The critical heat flux (8.5 kW·m-2), apparent thermal inertia 0.20 ± 0.02 kJ2·m-4·K-2·s-1 and ignition temperature 324 ± 105°C of spruce wood board increased up to 18 ± 3 kW·m-2 (critical heat flux), 0.68 ± 0.03 kJ2·m-4·K-2·s-1 (apparent thermal inertia) and 475 ± 27°C (ignition temperature) by the installation of electrical cables on the surface of spruce wood board.

Determination of the critical heat flux for floating flooring

The paper deals with the possibility of floating flooring ignition due to radiant heat. Samples of floating flooring with dimensions of 100 ± 1 mm x 100 ± 1 mm and thickness of 6 mm were thermally loaded by different densities of external heat flux. The flaming combustion was initiated either solely by means of radiant heat, or in combination with electric spark igniter. Cone calorimeter was used for the determination of the critical heat flux. Time to ignition for each sample was recorded and the obtained data were used for the calculation of the critical heat flux density.

Impact of electrical cables embedded into oriented strand board on critical heat flux

The paper deals with the research of electrical cables embedded in surface grooves of OSBs and its impact on the critical heat flux. An OSB type 3 board (structural board for use in dry or humid environments) and an electrical cable with fire reaction class B2ca have been investigated. Four different configurations of grooves were investigated. The first configuration consisted of an OSB without grooves (control sample). The second configuration consisted of an OSB with a single groove in the centre in which the electrical cable was mounted. In the third and fourth configurations, there were three and five grooves, respectively in which the electrical cables were mounted (the width of the grooves and the spacing between them was 9 mm). The critical heat flux was calculated from the ignition times at five different heat fluxes (30, 35, 40, 45 and 50 kW.m-2) by using a cone calorimeter. The obtained data showed that the OSB without grooves (first configuration) shows the lowest critical heat flux (8.6 kW.m-2) and the lowest standard deviation of ± 0.5 kW.m-2 (lower ignition resistance) compared to the other configurations (critical heat flux in the range from 9 to 10 kW.m-2 and standard deviation from 3.1 to 3.2 kW.m-2).