Impact of Selected Electrical Cables Slope on Flame Out Time and Flame Spread

The aim of the research described in this paper was to study the impact of the electrical cables slope on the flame out time and the flame spread rate. Measured cables were thermally loaded by methanol flame (diameter of the container was 106 mm) at seven different slopes with respect to the horizontal plane (the slopes were 0° – horizontal orientation, 15°, 30°, 45°, 60°, 75° and 90° - vertical orientation). The first tested electrical cable was a copper three-core power one resistant to the flame spread with circuit integrity of the cable system during 30 minutes under fire (cross-section of each core was 1.5 mm²). The second tested electrical cable was a copper two-core signal one resistant to the flame spread with circuit integrity of the cable system during 30 minutes under fire (cross-section of each core was 0.5 mm²). The first electrical cable did not show reaction to fire class. The reaction to fire class of the second tested cable was B2_ca, s1, d1, a1. The obtained results proved that slope had virtually no impact on the flame out time and the flame spread over the tested cable surface (tested cables of all slopes stopped burning after 1 to 5 seconds after methanol flame burned out). Likewise, the flame spread was only negligibly beyond the border of flame action for each cable slope.