Question

Why do we use a number of thin insulated wires in place of single thick wires in cars and house wiring?

Answer 1

1. Copper is a very good conductor of electricity and is used extensively as electric wires in cars and hose wiring.
2. To make these wires and cables more economical, the prime objective is to optimize the amount of copper per unit length that can carry a certain rated current through itself without being damaged or burned.
3. In house wiring, the current flows are of alternating nature.
4. One of the properties of alternating current is that it has a tendency to flow on the surface of any conductor. It means the flow of alternating current is highly concentrated near the circumference, instead of being evenly distributed in the whole cross-section of the conductor.
5. This tendency is increased with the increment of frequency of the alternating current. This phenomenon is called the ‘skin effect’.
6. The skin effect concludes that flowing a higher amount of AC requires more circumferences instead of a more cross-sectional area of the conductor.

Hence, instead of a single copper strand, a copper wire has numerous multi-strands that increase its circumference dimension so that for the same amount of copper, a wire of a higher-rated current can be manufactured. A multi-strand wire also offers more mechanical strength than a single-strand wire.