Final answer:
The claim that high-voltage wires are wrapped in an insulating material is false; though they are supported by insulators on the towers to prevent electricity from grounding.
Step-by-step explanation:
The statement that high-voltage wires are insulated is false. While it's true that the wires you see on tall metal-frame towers are indeed held aloft by insulators, these high-voltage wires themselves are not wrapped in an insulating material.
The insulators are crucial for preventing the electricity from traveling down the towers to the ground, which would be dangerous and render the power lines ineffective.
However, the wires are bare because they are suspended high above the ground and far from objects that they could come into contact with, which reduces the need for insulation. Moreover, at such high voltages, the thickness of insulation required would be impractical and extremely costly.