Crosslinkable insulation materials, which are commonly halogen-free, for use in wire and cable applications are provided. The insulation include a crosslinkable thermoplastic polymer and flame retardant material. The flame retardant material may include a metal hydroxide flame retardant, such as a magnesium, calcium, zinc and/or aluminum hydroxide. The crosslinkable thermoplastic polymer includes silane-grafted polymer blend, which includes a polyolefin plastomer blended with one or more other thermoplastic polymers. The crosslinkable thermoplastic polymer may be curable by exposure to moisture and may include moisture curable silane functionality in the crosslinkable thermoplastic polymer.