What is a common insulation material used in electrical cables?

PVC (polyvinyl chloride) is a widely used insulation material in electrical cables due to its excellent balance of properties. It is cost-effective, durable, and offers good resistance to moisture, chemicals, and flame, making it suitable for a variety of environments. The flexibility and ease of manufacturing PVC also enhance its application in cable production, allowing for easier handling and installation.

While other materials like rubber and polyethylene are also utilized, particularly in specific applications, PVC's versatility and performance across many general-purpose uses make it a common choice in the industry. Fiberglass, while used in some specialty applications, is generally not recognized as an insulation material for electrical cables in the same way that PVC, rubber, or polyethylene are. Thus, PVC’s attributes and utility in a broad range of electrical cables solidify it as the correct answer.