Why aren't wires between telephone poles pulled tight?

Answer 1

because for expansion and contraction.

A2

There is enough tension in the wire to keep the sag to a minimum. The sag is known as a 'catenary'.

If they were tensioned enough to remove the catenary, the strain would be too much for the wire and the poles. The poles would bend and the wire would break.

The sag is a compromise.

Answer 2

Electrical wires are made up of copper which is a metal, metals conduct heat and electricity. The main reason they conduct heat and electricity is because they have additional electrons , when heat is applied it provides energy to these electrons, this additional energy makes them move out of their original shell thus expanding the atom structure. This overall expansion of the shells makes the entire wire expand to a certain extent. Similarly the exact opposite is the case when metal is cooled ie at night, the atoms receive less or no energy from the sun this makes them go back to a more stable state and thus contracting to it's initial or even to smaller size depending on the surrounding temperature. Because of this phenomena the wire undergoes expansion and contraction every single day, thus if the wires were tightly held in the long run the wires might get snapped because of the contraction it faced.

Answer 3

To allow for the expansion in Summer and contraction in Winter of the wires. If the wires were tightly strung on the poles on a warm, sunny day, on contracting in the cold of Winter, the wires could damage the fittings that hold the wires to the top of the poles, fall down or even snap.

Answer 4

wire expand and contract with temperature changes

Answer 5

As temperatures rise and fall, the material in the wires expands and contracts. The wires need slack so that they can do this.