Everyone learns in school that water conducts electricity. So why don’t the high-voltage power lines crisscrossing our skies short circuit during rain?
The Nature of Water Conductivity
You might have missed a few physics lessons in school. Not all water is conductive!
We often learn about how the world works not from textbooks or scientific articles but from our own sometimes unfortunate experiences. For instance, you or someone you know might have tried to plug in a kettle or another electrical appliance with wet hands and received an electric shock. It’s fortunate if the wire quickly dries off, because otherwise, this could lead to a short circuit, fire, or even an explosion.
What is a Short Circuit?
A short circuit is an unintentional connection between two points in an electrical circuit with different potentials, causing a sharp increase in current and a potential fire hazard.
Why Water Causes Short Circuits
If you’ve noticed a short circuit when an electrical wire comes into contact with water, remember that it wasn’t distilled water. It likely contained impurities such as metal ions (like calcium, magnesium, and iron) and halogens (chlorine, bromine, iodine). These impurities increase the water’s electrical conductivity.
Such water can potentially create electrical connections in parts of the circuit where they are not needed, causing the current to flow through unintended paths, resulting in a short circuit.
How Power Lines are Protected from Short Circuits
So, if impure water conducts electricity and can cause short circuits, why doesn’t this happen with high-voltage power lines?
- Purity of Rainwater:
Rainwater falling directly from the sky is quite close to pure. Even if it contains free ions, they are in very small amounts.
- Insulators:
High-voltage power lines are equipped with electrical insulators to separate circuits and prevent them from touching, thus preventing unintended paths for the current. These insulators are made from materials that do not conduct electricity or conduct very little, such as ceramics or glass.
If you look closely at these insulators, you’ll see they have many bell-shaped grooves. These grooves prevent water droplets from connecting, effectively eliminating even the slightest chance of conducting electricity.
- Distance Between Lines:
Power lines are spaced far enough apart to ensure that rainwater cannot create an arc between phases. Regular maintenance is also conducted to inspect insulators and wire coverings.
By combining the natural properties of rainwater, the use of insulating materials, and strategic engineering design, high-voltage power lines are kept safe from short circuits, even during heavy rainfall.