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Why use aluminum cable instead of copper in overhead lines?

As for the wiring used in the home, basically all of them use the copper conductor cable. Aluminum cables hardly appear in homes. However, outdoor power circuits continue to use aluminum cables. So why not use copper wire outside?

In the following article, we explain the reasons that aluminum cable is more appropriate for outside power lines from several points. 

characteristics of aluminum cable

Weight of Aluminum cable vs copper cable

1. Overhead lines are supported by poles or towers to hang the cables in the air. Since overhead line cables are suspended in the air, the weight of the cables must be taken into account. In fact, the conductivity of aluminum is second only to copper. The conductivity of aluminum is about 2/3 of copper, but the density of aluminum is only 1/3 of copper. Therefore, in the aerial, aluminum wire is more appropriate.

2. Outdoor cables are also affected by their own gravity and environmental changes. For example, it will be affected by changes in air temperature, also known as thermal expansion and contraction. The aluminum conductor is better than the copper conductor in terms of thermal expansion and contraction, so it is more appropriate to use the aluminum cable for overhead lines.

Dense oxide of aluminum cable

1. Aluminum conductor is suitable as bare overhead wire because it will form a dense oxide film in outdoor conditions. This prevents it from corroding and rusting from air and rain. In addition, the oxide film has a certain degree of insulation. Therefore, aluminum wire is more widely used in outdoor circuit systems.

2. Copper wire laid in the open air cannot form a dense oxide film. And over the years, a layer of copper patina may appear that will affect the transmission of current. Therefore, the copper conductor is not suitable for bare overhead wires in the open air.

Aluminum cable price

1. The price of aluminum wire is much cheaper than that of copper wire. Now, the price of each ton of copper can be almost close to $10,000, while the price of aluminum is less half or less. Therefore, considering the price, the copper conductor is also not used for the outdoor cables due to the huge quantity.

2. The demand for the number of overhead line very high. From the point of view of investment, a more suitable and economical material should be chosen. Therefore, aluminum cables are the preferred option. This is the same for all countries in the world.

Characteristics of outdoor electrical cable

1. By analyzing the characteristics of high voltage cables, it is also possible to know why aluminum cables are used. For the common formula in the circuit is the power P = UI. Since most of the outdoor wires are high voltage, the current is very small.

2. The amount of electrical energy delivered per unit time in any one of the outer circuits is, in fact, almost fixed. So, in the case of fixed power, the current is reduced while the current voltage is increased. The aluminum cable fully satisfies the current demand of outdoor lines, so it is not necessary to use copper conductor.

These are the main reasons why aerial cables are aluminum and not copper. The main thing is that the mechanical properties and the price of the copper cable are more suitable for indoor cables. For outside power lines, aluminum cable is more appropriate.
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