PVC Cable Burning Behaviour and Intumescent Protection: Small-Scale Tests and the Browns Ferry Lesson

Electrical cables are present in nearly every building and industrial site. In a fire they can act as the starting point, as a path along which flames travel, and as a major producer of smoke. This paper presents laboratory results for a single-core PVCinsulated copper cable and a literature review of passive fire protection (PFP), with attention to intumescent coatings. Two standard tests were run: vertical flame propagation under IEC 60332-1-2, and cone calorimetry at 40 kW/m² under ISO 5660-1. Both vertical specimens passed. Flames died out within 5 s of removing the burner, and charring reached only 80 mm and 160 mm along a 600 mm length. In the cone calorimeter the insulation ignited at 125 s, peaked at 114.89 kW/m², gave a total heat release of 70.81 MJ/m² and a smoke production rate of 0.175 m²/s. The material therefore shrugs off a small flame but, under sustained radiant heating, becomes a long-lived source of heat and smoke. The review part explains how intumescent coatings function, the product families available, how they fail, and how the 1975 Browns Ferry fire reshaped cable-protection rules.