Question

Overhead electrical wires are not insulated because:
A. air is a good conductor
B. air is a bad conductor
C. air offers friction
D. to prevent theft.

Answer 1

Hint: The main reason is that the transmission line is carrying extremely high voltage and it would require a lot of thick insulation to absorb the heat produced by such high voltage. The chances of touching the wire is very less because they are at an extreme height from the ground.

Complete step by step answer:
Generally Overhead electrical wires are not insulated because of the wires hanging between the posts which are higher in height. So, there is air acting on the wire. Overhead wires are not just a simple copper wire but it is actually made up of a combination of aluminium and steel which is made of steel rods and so the weight of the conductor is high. If we add more conductors, it would be resulting in intense pressure on towers.
Actually, the transmission lines are insulated by air. It is surprising but the current and the voltage in the three phases of overhead lines. If we insulate the wire, it consumes high cost and it is surrounded by many objects to block the air to insulate them.
Therefore, Air is a bad conductor.

Hence from the above options, option B is correct.

Note: If the overhead wires are insulated it is too costly to insulate these wires. Because imagine, using insulation on millions of Kms of transmission. It isn’t practically not possible. But in the case of underground cables, insulation is required so that the live cables don’t touch earth and get shorted. In overhead wire air naturally insulated.