Final answer:
High-voltage transmission lines are not insulated; air acts as a natural insulator, and insulating such lines would be impractical due to cost and complexity.
Step-by-step explanation:
The statement that the high-voltage wires which are attached to tall metal-frame towers and are held aloft by insulating connectors are wrapped in an insulating material is false. Typically, these high-voltage wires, also known as transmission lines, are not insulated because the air around them acts as a natural insulator. They are supported by insulators that are made of materials such as ceramic or glass to keep them from coming into contact with the towers and grounding the electrical current.
Additionally, insulating such high-voltage lines, which can carry tens of thousands of volts, would not be practical due to the substantial insulation thickness this would require as well as the cost and complexity it would add to their installation and maintenance.