US Patent 9773585 Fire resistant coaxial cable

A fire-resistant coaxial cable is described in which the dielectric between the central conductor and outer coaxial conductor can ceramify under high heat. The dielectric is composed of a ceramifiable silicone rubber, such as that having a polysiloxane matrix with inorganic flux and refractory particles. An outer wrap of ceramic fiber yarn surrounds the outer conductor and continues to insulate it from the outside if a low smoke zero halogen jacket burns away. Embodiments include those with durable corrugated outer conductors or flexible braided outer conductors. Methods of testing and installation are described.