Why are power lines all completely covered with insulation?

I date a widow who lost her husband, because he was doing construction work and some equipment moved and touched a power line. My daughter and her husband lost a friend male to a power line. His friend was sailing in a boat, mast and sail not to delete the line but hit the mast and died. I had a coworker who was working on the roof of a house and head accidentally hit a high voltage power line. He fell off the roof and fell. While in the hospital, the doctors think the shock his heart stoped, but the impact with the ground was good because it is likely that his heart began back. The electrical, badly damaged one of his feet and that the damage to teeth. So, how is that these lines are not insulated? What is the excuse?

The air is an insulator, so even a bare wire is immersed in the insulation. For high voltage lines, there is usually no reason to expect someone to contact them – there's no real reason to isolate more than air. Accidents happen, as the experience, but it is difficult expensive to justify measures that prevent accidents rare. The money for safety equipment is better spent on more risks people are exposed, or on safety of the few that are normally exposed. If using plastic insulation, should be 1 / 2 inch to 2 Incles thick, maybe more, owing to high voltages used (sometimes 700,000 volts). That would not only increase costs but also the weight of the cable – so they need support, so the towers and lines transmission would cost even more.

Holland America Lines MV Zuiderdam sailing from Port Everglades