Why can not the aluminum cable be used in electrical wiring?

PUE -7. Chapter 2.1 Wiring. Scope, definitions

2.1.49. For stationary wiring, mainly wires and cables with aluminum conductors should be used.

PUE.7th edition. Section 7. Electrical equipment of special installations. Chapter 7.1. Electrical installations of residential, public, administrative and domestic buildings

"7.1.34. Cables and wires with copper conductors should be used in buildings. Supply and distribution networks should generally be made with cables and wires with aluminum conductors if their design cross-section is 16 mm2 or more."

A wire or cable with aluminum conductors cannot be properly fixed; it constantly climbs out from under the contact. Periodically, all contacts have to be checked and tightened. In addition, it is very brittle, and it also oxidizes decently. When using various terminal blocks to connect the wires, it is necessary to use quartz-vaseline paste, otherwise the contact point will be constantly heated and the connection will be very unreliable and this is all due to oxidation. Now everyone who makes repairs in their apartment changes the wiring to copper, as there are much fewer problems with it than with an aluminum wire. If there is no money to replace the wiring immediately in the entire apartment, you can do as I did - change the aluminum wiring to copper room by room. It turns out not so expensive. It is better not to waste time on aluminum and get rid of it, otherwise you will have to open the gates again after repair. This will be fun.

Aluminum is cheaper and lighter than copper, has a satisfactory current transmittance, but is inferior to copper in conductivity. The disadvantages of aluminum are related to the complexity of mounting electrical contacts. Aluminum oxidizes very quickly and an oxide film forms on its surface, which has a high resistance. It worsens the state of contact. Interestingly, to melt the oxide film of aluminum during welding, a temperature of about 2000 g is created. C, although the melting point of aluminum is only 657 - 659 degrees! When the compound is heated and then cooled, the tightly pinned conductor "flows" out from under the contact, the contact is deformed. Then, aluminum has a large thermal conductivity and this leads to heating of the core, which is adjacent to the welding site. As a result, the insulation of the wire overheats and its properties deteriorate.

Well, of course, aluminum cannot be completely forbidden, for example, we have such a microclimate in treatment plants that copper doesn’t roll. 1.5 squares in the open rot literally in 2-3 years. It is not always advisable to seal all connections with contact paste because of the low qualification of electricians, a large number of connections, etc. Aluminum under such conditions lasts much longer.

Semen Deruzhinsky,
By the way, the thermal conductivity of copper is almost two times higher than that of aluminum.
Aluminum - 221 W / m * s
Copper - 407 W / m * s

Stas, !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

PUE -7. Chapter 2.1 Wiring. Scope, definitions

2.1.49. For stationary wiring, mainly wires and cables with aluminum conductors should be used.

What did not finish? This is actually 86 years old .....

For exceptions see 2.1.70 3.4.3 3.4.12 5.5.6 6.5.12 6.5.14 7.2.53 7.3.93

Namely
- Open attic wiring,
cabinet wiring wires ....
In general, most of those chapters have already been canceled ....))

The main thing is DNAP 0.00-1.32-01. Rules for the installation of electrical installations. Electrical equipment of special installations.

Do not grind nonsense! Properly made aluminum wiring lasts for decades! In St. Petersburg Khrushchev, this wiring is about 50 years old. And if there all sorts of blockheads did not climb into the boxes, then now there are no problems. I worked for 8 years at a substation. Aluminum cables were contacted with copper busbars (the contact spot was smeared with tsiatim). The puff was checked once a year. There were no problems. So do not scold Al.

Now, of course, I am a supporter of copper.

If you had aluminum wiring, then the new one should be installed only copper, since it has a much longer shelf life.

In fact, aluminum wins more than twice as much in conductivity per unit mass, and also wins more than twice as much in cost per unit mass. Copper is economically disadvantageous every 4 times. It is sufficiently ductile and bends no worse than copper, only slightly less durable (with identical cross sections).

Material scientist

What x..on aluminum has better conductivity?

George,
And you read carefully! ONE UNIT OF MASS! Or kakgo x .. on you physics at school
skipped it!  

Everything has the right to life, and aluminum and copper. Of course, a noblewoman is better than a cook, but when there is no noblewoman, they are treated as a cook. Both this and that have their pros and cons. Better yet, silver and gold wires ...

Boris,
And the better the gold wires?

For VSF: their conductivity is higher. True, the unit cost of kakbe is also not far behind.

At the cottage I changed the input cable from the column to the counter, there was a choice of copper 4 mm2 or aluminum 6 mm2, I chose aluminum. At a price almost 4 times cheaper, with the same characteristics. Competent aluminum wiring lasts a long and high quality, the main thing is to do good soldering and stretch contacts once every 1-2 years, and of course not to overload them beyond the norm. Copper is not so super, you also need to stretch the contacts, etc. Copper wins, IMHO, it’s a convenience to work with copper, because with the same characteristics, the copper cross section is less than that of aluminum and copper is more resistant to fracture, it’s also more convenient work, you can bend at least somehow, but otherwise aluminum is no worse, again IMHO.

What to argue about? For aluminum air! For the liner to the ASU is the same aluminum. But the apartment is already copper. So much more rational and cheaper. Large sections aluminum, small copper. This is done all over the world, including in the USA.

When an electrician, housing and communal services served residential buildings of 1960-1990x. In fact, there were no particular claims to aluminum of all kinds, except for the economic way to carry out the networks (as they wanted and did, let them try to find the wiring under the plaster), and the ugly operation of the house networks by consumers. Copper, of course, surpasses aluminum in many respects, but for people with limited abilities, price remains the main criterion. Still, the networks made by electricians half a century ago have served to this day, and today's generation on this issue is probably inferior to them. IMHO. The main thing is hands and head.

In the article and in the comments, one negative property of aluminum is not mentioned - it is a fire hazard. If a jet of molten metal is directed from a height of several meters, then the temperature of droplets in aluminum will be higher at the time it hits the floor than at the top, and copper will have a significant drop in temperature. This is due to the fact that a drop of aluminum moving in the air heats up and flares up like sparklers. Those. with a short circuit of the wires on the ceiling, more heated particles will fall onto the floor than in the case of copper, and if we take into account the relatively low reliability of the contact connections of aluminum wires, this further determines the choice of copper wires.

A significant advantage of aluminum is its significantly lower cost compared to copper. At the points of reception of non-ferrous metal per kilogram of aluminum, they are 5-6 times less than per kilogram of copper.In addition, the aluminum cable weighs much less than copper. Accordingly, aluminum is less attractive to thieves. Several times I had to re-run the copper cable supplying the garage due to theft. In the end, I decided to hold aluminum.

What about the reliability of electrical wiring, it all depends on the quality of the contact connections. If the contact connections in the junction boxes, as well as in the places where the cable is connected to protective devices, sockets and lighting devices, are reliable, then aluminum wiring is not inferior in reliability to copper. Qualitatively mounted aluminum wiring will last for more than a dozen years. And if you draw a separate line to each outlet, then the reliability of the wiring will increase significantly, since there will be no intermediate contact connections, as the most vulnerable places of the wiring.

Despite the many advantages of copper cable, in our time the overwhelming majority prefers aluminum, arguing their choice with its relatively low cost.

When wiring, it is permitted to use wires and cables exclusively with copper core. To be completely fair, in the Rules for Electrical Equipment (PUE) there are assumptions for using wires with aluminum conductors with a cross section of more than 16 m2, but hardly anyone will use this norm, therefore, a copper core in electrical wiring is the only right way!

Over the past decade, the number of equipment installed in apartments has increased tremendously, and at the same time, the electric power consumed by this equipment has increased. Accordingly, the load falls on the electrical networks laid in the walls of our apartments and entrances.

This is especially true of old-style houses, where aluminum wires are often laid, which, under the influence of time and heating, begin to collapse and become unusable. Therefore, if you do not want to remain without light for several days, or if you want to strengthen your fire safety (malfunctions in old networks are a common cause of fires), it is better to repair and replace home networks in advance.

As for aluminum, it is better to say right away - it is not worth using it. Of course, the cost of its purchase is less tangible, but it quickly deteriorates, oxidizes faster, is brittle and requires large cross sections, which of course will affect the convenience of laying it. And do not forget about the Electrical Installation Rules, in which it is noted that aluminum wires and cores should not be a cross section of less than 16 square meters. mm

It can be seen from the above that copper comes to the fore. In copper, the value of electrical resistivity is higher than in aluminum, it is less susceptible to heat, which affects the aging and destruction of insulation, and, accordingly, reduces the chance of electric shock and fire in the apartment. Contact compounds are more durable than aluminum, and copper itself is more resistant to deformation. The minus of copper is only in price, although it is unlikely to hit your pocket, but the newly laid copper wire will calmly serve you for about 30 years.

Copper wires are also on sale (copper goes only along the surface of the conductor, the rest is of various kinds of alloys), the conductivity of such wires is worse than that of pure copper, they are more rigid, but resistant to external influences.

Toolmaker, Adjuster of electronics of CNC machines, Electrician, Power Engineer, Electromechanic - these are the stages of a long journey and from a height of 50 years I can say the most important thing - it's never too late to learn. Read the English and French theory.The British have fuses in the plugs 3-13A and you can’t always put a friend on the right side of the plug, the French have a room shield for the number of automatic machines like a cabinet distributor at an aircraft factory, each device has its own counted automatic machine
Repairing other people's cutters and wiring installation takes about half in work
Regarding the topic: The general correctness of all who shared the wiring - prefabricated (pre-office) aluminum on copper,
All that vibrates, moves to connect the stranded copper (PV3) (PVA), it is for extension cords in rooms, and in the summer on the street, In winter, rubber KG is better than KGN
To an aluminum wire up to 16 mm - no, to an aluminum cable from 16 mm - yes An aluminum cable, and if armor and oil-filled lie in manure 150 years and nothing will happen to it from copper there will be nothing left
Try to avoid direct contact of copper with aluminum. After all, for example, there are TAM tips or tinned copper terminals. Washering with 3-D metal is still heresy. The conductor is not a bolt, but a stripped maximally large joint
Do not drill the tips for a larger bolt, do not reduce the bolt by more than a step, but take a larger tip For example, a 35 mm wire can easily be inserted on a 35 mm sleeve that is clogged with 70 TA with a light hammer by tapping the hammer and crimped 2 times with 6 hydra, and then be removed with a HERE and stripped to a mirror shine (but not with paper sandpaper) and then on a 12 bolt 2 nuts and washers are thicker and wider. Such an aluminum connection, coupled with an old-mode 400a breaker, will last forever, providing 60 kW of 3-phase load. I saw tags from the 50s of the last century and on the web where there was no human hand
The thinnest part of the wiring where it breaks - contact
Wiring with aluminum SIP in air is without a doubt the best
Lighting 1.5 mm2 copper and 3-6 A automatic machine German and US wagons twisting with putting on 2 screw terminals (only opaque, but blue or yellow, crimping with cap
We do pressure testing with 6-sided hydraulics (I still store chains up to 240 mm and lever up to 70 and for copper and aluminum crimping) soldering has worse conductivity, and welding without flux spoils the metal structure
PPEs, to be honest, I consider only heresy except for lighting with preliminary cleaning of the twisted ends up to 3 pieces
A junction box is a penny thing so we do not connect the lights with a cable
Power (outlet) -2.5 mm2 copper and 13 A automatic twisting machine with crimping
Do not neglect 3 and 5 residential and fire safety - VVG NG LS and so on
Black PND corrugation is very convenient. A hide in a tree is a metal pipe for carving in metal boxes, at least a metal hose with plastic sleeves
Pull all screw contacts 2–3 times with an interval of six months, then inspection and trial selective broaching
We isolate sleeves, tips with a white insulating tape in 2-3 layers or with heat shrinkage - it is better to see the heat pass periodically with an IR non-contact thermometer
Wiring only in straight turns of 90 degrees Turn radius 10 cable diameters
God forbid from the use of a grover or it will burst or sag - only a washer bolt and 2 nuts
Try not to save money during installation (high-quality components), direct hands of a good electrician with a bright head, that is the key to success.
And at night, read the PUE, PTBEP, a directory of rural electricians in Australia.
It is from installation errors that the wrong fears are born.
APPLY UZO (but it is correct) it will save your lives.
Love the electrician and the train as yourself.
And aluminum was called the metal of the future in the recent past.

There is a significant advantage of aluminum: it melts during a short circuit inside the wire, breaking the circuit without igniting the insulation. With copper, such a trick is harder to do.

According to the PUE, internal electrical networks should not be carried out by cables and wires with copper conductors. It is allowed to use cables and wires with aluminum conductors with a cross section of at least 16 mm2 in the supply and distribution networks.The power supply of individual electrical appliances related to the engineering equipment of buildings (pumps, fans, heaters, air conditioning units, etc.), except for the equipment of fire fighting installations, may be carried out with wires and cables with aluminum conductors with a cross section of at least 2.5 mm2.

The more I start to delve into wire connections, the more different versions can be found. Unfortunately, those who are directly responsible for these compounds usually do not read much :( Yes, and in the 21st century, with this level of technological progress, it is high time to put an end to this dispute, but in practice, everything is back:

For example, you can find a video, yes, and as the article says, the problem is the transient resistance of copper. In practice, I have, when tested with a load of about 20 Amps, and an aluminum wire of 2.5 square meters. mm, its heating is certainly substantial, but the fire did not work out from it. Moreover, the place of twisting also turned out to be less hot ... Why so? Next, let's talk about the connection of copper and aluminum - a lot of words can be found about a galvanic pair, and proto, how best to connect such wires. As a result, some offer terminal blocks, others solder, others offer twisting, and others offer bolted connections. There are also GAM-type sleeves, but in the end, not one option has an exact definition - and in fact, all of them are not correct. And then what to use, and who will answer all the questions?

About the aluminum wiring. In apartments, aluminum wiring is more profitable than copper. This is tested in practice. You must be able to calculate the cross-section of the wire under the load on the network. and twisting connections will be more reliable than any terminal blocks. If the wiring is not done correctly and seriously, then the copper wiring burns no worse than aluminum. And yet, the twisting must be done dense. To do this, two pliers are needed. That is the whole discussion.

And why don’t you mention that oxidizing a copper wire to green also threatens current throughput? Advertise on an expensive copper wire?
If the track is straight without bends, you can lay an expensive aluminum wire, then you can take it out with a copper wire.

Aluminum is brittle, like a bastard. That's all.

In October 2017, the Ministry of Energy issued the "Safety Rules for Power Receiving Installations. Features of the electrical wiring in buildings with conductive copper conductors or aluminum alloy conductors." This means that aluminum was again allowed to be used in electrical wiring.

Do not talk nonsense!
In which vocational school did you wipe your pants?
They did not prohibit the use of aluminium in electrical wiring.
But you probably opened the physics textbook from the wrong side or held it upside down.
"much more powerful," smiled. In the characteristics of conductors there is no such concept of "power". There is the concept of "wire cross-section" and "resistivity." "Conductivity", the electrical conductivity of a conductor depends on these two characteristics. But the current density will depend on the cross section of the conductor and the load power. The cross section of the conductor is selected according to the current consumption of the expected load so that the current density in the conductor does not exceed its maximum permissible, plus the "safety factor".
The weight of the conductor is taken into account by the project unless in aircraft construction and in the space industry. Every gram is important there.
A well-made twist has a cross section much larger than that of the conductor itself and no oxide prevents it from working reliably for decades. Transition resistance in this case is more dependent on crooked hands and blunt brains, whether aluminum or copper, is not important. And if you also apply welding of aluminum twists, then you can forget about oxides and transition resistance.
PUE you also did not read, it is immediately noticeable.

In addition to mine, read the comments above. I support and approve of them !:
Comment 7 Karamaz777
Comment 15 Dmitry
Comment 16 Roman
Comment 17 Igor Zavarov
Comment 26 Taimuraz
Boris ...
"comment 12 Boris"

There is such a saying, "For the lack of a cook, cook e @ ut."
Anisu ...
"Comment 18 Anise"
In order for a substance to warm up during friction against air, it must be dispersed even to the first cosmic speed. Read the physics of Soviet times. It really is based on PHYSICS !!
Modern can lie ...

We must also take into account the higher strength of copper (due to elasticity) compared with aluminum. During installation, this is a very important factor, given that when laying the conductor will have to be bent at different angles (and sometimes repeatedly). Due to bends, aluminum wiring has microcracks and cracks, which can lead to a decrease in conductivity in this area and, as a result, to a wire breakage.