Why are overhead electric wires and cables dangerous?

Answer 1

Absolutely, If you come into contact with them you can be seriously injured or killed. There is an enormous amount of power running through them. There is also the proposed idea that living near them can increase ones risk of cancer due to the strong electromagnetic fields produced by the lines. I would go further and warn that you don't even have to come in contact to be hurt. Very high voltages can arc over some distance, so even getting close can kill. If you encounter a downed line, the current flow through the ground can produce a 'voltage gradient'. This means as you get further away from the line, the voltage present on the ground decreases. If you take a step toward the line, one foot could be standing where the voltage is, say, 500 volts. No problem so far. But as you step, the other foot could land where the voltage is 700 volts. Oops, now you have a voltage from foot to foot of 200 volts! Nasty. Bottom line - stay far away from high voltage lines! If one is down on or near your vehicle, avoid the temptation to jump out and run. Remember the voltage gradient. Wait for rescue workers to de-energize the line.

Answer 2

Yes, of course high voltages are always dangerous! This is why bare high voltage conductors have 'safe limits of approach' which increase with voltage. Moving within the safe limit of approach could result in a flashover and the resulting energy is more than high enough to burn you to death (forget electrocution!). This is why people who work with high-voltage systems are specially trained to do so.