Abstract: This study investigates the effects of inclined angles and cable spacing on fire spread behavior of parallel dual cables through theoretical analysis and combustion experiments, with particular focus on flame morphology, mass loss rate, and fire spread rate. The results reveal that under constant cable spacing, the flame height, mass loss rate, and fire spread rate increase with greater inclined angles. At fixed inclined angles, these three parameters initially increase then decrease with expanding cable spacing, peaking when the spacing equals 1 times the cable diameter. During combustion, the mass loss curve exhibits irregular step-like abrupt changes caused by periodic detachment of carbonized layers. The initial detachment of carbonized layers predominantly occurs 200~400 s post-ignition, demonstrating significant temporal randomness. For cables of identical length burned at the same inclination, the zero-spacing configuration yields the minimum total mass loss. A predictive model for fire spread rate under horizontal and inclined conditions was developed, effectively correlating the spread rate with both inclination angle and cable spacing.

Key words: parallel dual cables, inclined angle, cable spacing, heat transfer, fire spread