Final answer:
High-voltage wires on metal-frame towers are held up by insulating connectors but are not wrapped in insulating material; air serves as the insulator.
Step-by-step explanation:
The statement is false. The high-voltage wires that are connected to tall metal-frame towers, known as transmission lines, are indeed held aloft by insulating connectors; however, these wires are typically not wrapped in an insulating material.
These transmission lines are designed to carry electricity over long distances, and because they operate at high voltages, they are suspended high above the ground and separated by air gaps at insulating connectors to prevent electrical current from grounding. Insulating materials around the wires would be impractical due to the high voltages and the large physical size of the transmission lines.