Literally another 20-30 years, all wiring was aluminum, and in modern constructions and repairs, you will not find such. But what makes copper better than aluminum? Which wiring is better to use for the house: copper or aluminum? Where better to use aluminum and where copper? We tell you why the material of the wires has changed so quickly and irreversibly for the better. To date, the optimal solution for laying electrical wiring is the use of copper wires.
The use of aluminum was justified mainly due to the low cost of this material. Aluminum wires are lighter than copper, but they are a weaker conductor of electricity. The conductivity of aluminum is about 1.5 times lower than the conductivity of copper. Also, aluminum, compared to copper, is less resistant to stretching.
Aluminum wiring does not allow the use of energy-intensive appliances, such as induction hobs, ovens, automatic washing machines, etc. As a rule, such wiring requires replacement and modernization.
Currently, aluminum wires are used successfully, mainly with large cross sections, usually above 10 mm ². In this case, an important advantage of aluminum wire is that it is 70% lighter than copper. This increases the convenience of laying long and thick cables.
The decisive factor in the use of copper wires is a very good electrical conductivity of copper. Also, the installation of copper wires is easier than aluminum, mainly due to their greater flexibility and mechanical strength. Copper wires are not damaged by bending or twisting.
Copper is superior to aluminum in electrical conductivity. The electrical resistivity of copper is 0.017 Ohm * mm 2 / m while aluminum is 0.028 Ohm * mm 2 / m. That is, the electrical conductivity of aluminum is 65-70% of the electrical conductivity of copper, so for the same load, the aluminum cable will have to take a cross section higher than copper.
For example, it is necessary to feed a load of 5 kW. For it it will be necessary to take either a copper cable with a section of 2,5 mm2, for example, VVG 3х2,5, or aluminum AVVG with a section of 4 mm2.
The advantage of copper over aluminum for wiring
Both copper and aluminum are oxidized during operation under the action of air. However, oxidation in copper is much slower, and the film itself (greenish plaque) is quite easily destroyed, so it conducts current well (although the permeability deteriorates slightly).
In aluminum, oxidation occurs much faster, and the oxide film itself is very dense and conducts current poorly. Oxidized compounds on twists, clamps or terminals are often the cause of burning contact.
If you take the mechanical strength, the copper cable is more flexible and durable than aluminum. In the process of mounting the core has to be bent, for example, for connection in junction boxes and sockets. Copper cores can withstand repeated bending without damage, but aluminum only 5 – 10 bends, and then break.
Aluminum wiring creates special problems when you need to repair the connection in the junction box – the old aluminum already has microcracks, so with one wrong move the core can break and have to remove part of the plaster to pull out at least a little wire.
As for the ability of the conductor to dissipate heat. The higher the thermal conductivity, the better the metal dissipates heat. In copper, the thermal conductivity is 389.6 W / m * ° C, and in aluminum 209.3 W / m * ° C. That is, copper dissipates heat almost twice as well as aluminum. This is especially important at the joints where the wire is heated the most. At the same load, copper will be twice as fast to dissipate heat (or rather not heat up).
Advantage of aluminum over copper for power lines
If we consider aluminum for overhead power lines, then there is a significant advantage, they are still made of this metal.
The weight is largely determined based on the density of the metal. The higher the density, the heavier the conductor. The density of copper is 8900 kg / m3, and aluminum 2700 kg / m3. That is, with an equal volume of copper wire will weigh 3.3 times more than aluminum. For home wiring, this is not critical, as the wire lies in the gates, and for the overhead power line, this is an important indicator. That is why aluminum wire is used for overhead power lines.
As for the price, aluminum has a clear advantage. All the disadvantages of aluminum have affected the relatively low price, which is about several times lower than the price of copper, so overhead lines, as well as inputs to the house are performed exclusively with aluminum cable.
Experts often argue that it is better to use in wires and cables, aluminum or copper. These two metals have better, unlike other metals, electrical conductivity at a relatively low cost. To say that one of the materials is better than the other is simply not correct, although both types of wires have certain advantages and disadvantages.
Taken together, all factors are so important that aluminum wires and cables are widely used to transmit electricity over long distances (for example, between stations and substations, to connect end users to common electrical networks, etc.). Due to the low weight of aluminum wires, the load on electrical supports and insulators is reduced. From here it is possible to draw a conclusion that the aluminum cable of the increased diameter is more favorable to apply, than copper. However, aluminum has a number of negative properties – it is:
low manufacturability of further processing and use;
low service life;
low maintainability, and high-frequency properties of such a cable are not at the highest level.
Aluminum wire is rarely used in those places of electric machines, where a lot of weight is not only weight but also dimensions.
As for copper, as already mentioned, its electrical conductivity is one and a half times higher than aluminum. Accordingly, the heat loss (and voltage loss) in copper conductors will be one and a half times less than in aluminum of the same cross section. In addition, copper is less corroded.
Competition for the use of aluminum or copper has existed in the world for a long time (especially for industrial and domestic wiring), so the choice between them should be made by a qualified specialist depending on the specific situation.
Also do not forget that aluminum and copper cables can not be connected directly to each other, because it produces galvanic steam, in which aluminum is destroyed very quickly due to electrocorrosion, which impairs electrical contact. A place with bad contact will heat up, sparkle. As a result, the reliability of the contacts will decrease, which can lead to fire. Therefore, if necessary, the connection of copper and aluminum wires use steel terminals, connectors and adapters that prevent direct contact of aluminum and copper.
If your house is older than 20 years, and it has aluminum wiring – replace it, because the shelf life of aluminum is just 20 years. Over time, this metal loses its plasticity and can be destroyed at any time by external factors. New wiring is best done with a copper cable, taking into account the power consumption of the equipment.
As a rule, wiring standards for lamps and chandeliers require a copper two-core cable, more complex devices (requiring grounding, such as washing machines, computer, water heater) require the use of a three-core copper cable. Kitchen appliances require separate wiring. It is advisable to use a copper three-core cable up to 4 square millimeters.
If you have decided on the type of cable that is right for you, and you want to get impeccable product quality and highly qualified advice from our experts, before you buy a cable, contact the Zaporozhye Cable Plant MPKA.
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