The voltage of our home wires is only 220V. As long as we wrap them with a thin layer of insulation to prevent them from contacting the live wire, we can prevent electric shock.
The voltage of high-voltage wires is generally above 10,000 volts. If you want to wrap the line with an insulation layer, the thickness of the ordinary insulation layer is far from enough. The role of insulators for high-voltage wires is almost negligible. Because in the face of strong high voltage, air can also conduct electricity. For example, a high voltage of 10 kilovolts can break through more than 1cm of air for conductivity. At this time, the general insulation layer has no effect.
The insulation layer required for high-voltage circuits is much thicker than that required for household circuits, which will not only increase costs, but also require more technology. Moreover, the weight of the wires with insulation layers will also increase a lot, so the span of the line will be greatly reduced, which also increases the difficulty of construction. For example, in remote areas or places with rugged roads, the difficulty of construction will be even greater.
Assuming the above is true, even if the high-voltage line is successfully insulated, it will still result in poor heat dissipation. Poor heat dissipation will increase the consumption of electricity. Too thick an insulation layer will lead to poor heat dissipation, so the current carrying capacity needs to be reduced accordingly, which also increases the cost.
The only danger of exposed high-voltage lines is that they fall on the ground or buildings after breaking, which will cause a great risk of electric shock. The safe approach is to keep a distance of at least 20 meters to prevent electric shock accidents. As long as the outdoor overhead lines are erected to a certain height, there are no buildings under or near the overhead lines. Whether it is high voltage or low voltage, bare wires are used, which can reduce construction costs. With sufficient safety distance, the probability of electric shock accidents is extremely small, and there is no need to use wires with insulation.
Will rain conduct electricity?
Although rainwater conducts electricity, it is not connected.
The raindrops we see are actually the afterimages left in our eyes by the rain falling too fast. Rain actually falls drop by drop, and there is a large air gap between them, so rain is not conductive. Since there is no complete loop between the high-voltage line and the ground, the high-voltage electricity will not be conducted into the ground through raindrops, forming a short circuit, so it will not cause electric shock to people.
There is a ceramic insulator between the high-voltage wire and the iron tower, and its surface is smooth and does not accumulate water. The voltage tolerance of the insulator is very sufficient, and its disc-shaped structure greatly increases the creepage distance of the arc. In fact, the insulator is not afraid of being wetted by rain, but rain can wash away the conductive dust on it. The general public has few opportunities to contact voltage levels above 10kV, and electric shock accidents at voltage levels above 10kV rarely occur. Therefore, there is no need to use insulated wires for such high-voltage lines.
Post time: Sep-27-2024
