wood is an electrical  insulator
insulated_wire is electrical_wire. spark_plug_wire is not insulated_wire. insulator is material. electrical_insulator is insulating_medium. insulated_wire is not electrical_wire. spark_plug_wire is insulated_wire. building_wire is insulated_wire. building_wire is not insulated_wire. electrical_insulator is not insulating_medium. insulator is not material.