Write-off of expired goods documents. Warranty and actual service life of the electrical wire

When installing new wiring, the owner of the premises strives to do everything so as not to return to this operation, therefore, when carrying out repairs or during the construction process, he is always interested in how long the service life of the wire is. At the same time, confusion often arises in defining the very concept of service life - designers, cable manufacturers and electricians operate with different numbers. Therefore, first, let’s define the terminology.

Rated life

This indicator is theoretical in nature; it is used by designers when developing a project. Indicates the time period during which the cables, subject to compliance with the rules of their operation, will regularly ensure the delivery of electricity to end consumers. Example: for NYM cable operating in temperature range from -50 to +50 °C, the voltage load of which does not exceed 660 volts, this period is 25-30 years.

The practical meaning of using this concept is only in planning preventive maintenance and checking the condition of the wiring. Its actual service life may differ significantly from the nominal one.

As a rule, the service life of wires and cables guaranteed by the manufacturer is less than the nominal one. For example, in the case of the above-mentioned NYM cable, the designer includes in the documentation a nominal service life of 25-30 years, but the manufacturer provides a warranty of only 5 years. This means that if a breakdown occurs in a cable (or if it melts) that has served less than this time, the manufacturer will replace it free of charge.

But there is one important point. Free replacement is carried out only if a number of conditions are met:

the selling company ensured compliance with the storage conditions described by the manufacturer;
during transportation, the rules for its conduct, also described by the supplier, were not violated;
installation was carried out by an organization or individual with the appropriate license;
actual operating conditions did not go beyond the values specified by the manufacturer.

If the cable has been overheated, if a voltage higher than the maximum rated voltage has been applied to it, or if the maximum amperage has been exceeded, the warranty will be void.

More about guarantees

Cable manufacturers test their products on special test benches. Checks are carried out under conditions close to real operating conditions. The cables are laid in grooves and corrugations, and the wiring diagram includes connections with terminals and twists. After this, the wiring undergoes “strength tests” - average design loads are applied to the wires, peak loads (both in voltage and current), and the reaction to changes in temperature conditions is checked.

To determine the service life of a PVA wire, the sheath of which consists of soft vinyl, the humidity conditions in the room where the tests are being carried out are also changed, and in some cases the wire is tested for its ability to withstand UV radiation.

Checks are carried out at the launch of each new series, when introducing new equipment, when making any changes to technological process. Cables from different batches from different workshops are selectively checked. Controlled change physical characteristics cable, its electrical conductivity, resistance. The integrity of the braid is checked to see if it has begun to lose elasticity or collapse. By changing the test loads and constantly measuring the cable characteristics, it is possible to predict its condition after 10, 20, 50 years of operation in various conditions.

Actual service life

It is this indicator that is most interesting to the owner of the premises. At the same time, in practice, this is where the biggest difference is observed, since the actual service life electrical wires depends on a lot of factors that were listed just above. If the wiring is done correctly, the installation is carried out in compliance with all the requirements of electrical construction norms and regulations, the load power does not exceed the design value, and so on, then the wiring can last a hundred years. But if at least one of the many conditions is not met, the service life is shortened.

Much depends on the right choice safety circuit breakers. For example, a solid core with a cross-section of 2.5 mm will withstand a current of up to 25 amperes. A 16-amp machine will break out before such a wire has time to heat up from the increased load. A 40-amp machine will continue to work, but the cable will simply melt when a current of 32-35 amperes flows through it.

Another example: the cable powers a triple outlet in the kitchen, to which a microwave oven, coffee maker and electric kettle are connected. IN normal conditions these devices almost never work simultaneously. But all of them can be included, albeit for a short time, when preparing or holding a large family celebration. Even a short-term peak load will reduce the service life of electrical wiring.

Overheating is a separate issue. It can be caused not only by excess load, but also external factors. For example, after the wiring cable lines a fireplace was installed in the apartment and as a result some wire ended up in close proximity to the chimney. Constant heating will, in the worst case, lead to damage to the braid (and, of course, to short circuit), at best – to a change in physical properties, which will reduce its service life.

This is one of the first questions raised when replacing wiring within overhaul in a residential area. In general, the answer to this is most often unambiguous - copper. There are enough reasons for this - copper has lower resistivity, higher electrical conductivity, almost twice as high ultimate load in terms of power with the same cross-sectional area. Yes and service life copper wires more - 20-25 years (nominal) versus 15-20 for aluminum. But there are some nuances.

If something changes, then everything will change completely. Firstly, connection of copper and aluminum core– weak point in the wiring even when using a terminal made of a third metal (direct twisting in this case is generally unacceptable, since copper and aluminum form a galvanic couple). Secondly, partial replacement in order to increase wiring in some loaded area (for example, in a kitchen with a full set of household appliances) won't do anything. A copper cable laid in the walls directly in the kitchen can actually cope with the increased load on its own, but an aluminum cable running from the apartment panel to the junction box cannot.

Another point worthy of attention is the economic feasibility of such a replacement. Copper core still more expensive than aluminum, and if the house is not “packed” so much that the wiring really requires reinforcement, there is no point in changing it just because “aluminum is out of fashion.”

As for the duration of operation, there are houses in which the actual service life of aluminum wires is already 50-70 years, and the wiring in them does not need to be replaced. As already mentioned, it all depends on the specific conditions.

So, if the house is not stuffed household appliances, and the repair budget is limited, then you can change (if there is such a need at all) to aluminum. The only caveat is that in this case it will be necessary to carry out some kind of prophylaxis every two to three years. Its essence is to tighten the clamping screws in switches and sockets. Aluminum is plastic, the force exerted by the screw (or the contact pad pressed by it) leads to its deformation, the contact weakens over time, and poor contact is the most common cause of fires due to electrical wiring.

I think all owners of apartments and houses sooner or later are faced with the question of replacing electrical wiring, its rational use, advantages, disadvantages, service life, and so on. Today we will try to explain to our readers as easily and clearly as possible all the pros and cons of using aluminum wiring, and we will also figure out whether it is worth changing it to copper or not.

Advantages

From the very beginning, it should be noted that aluminum wiring is not the most reliable and high-quality and cannot boast of any outstanding merits compared to other types. But, nevertheless, it is precisely this type of electrical wiring that is installed in most old houses and apartments (Khrushchev). So, let’s start with the advantages of this type:

lightness (aluminum has less weight compared to other metals that are used in electricity as conductors);
resistance to corrosion (metal when exposed to air instantly oxidizes, forming a film that protects the rest of the wire from further corrosion).

Please note that the Electrical Installation Rules (EPI) prohibit the use of aluminum wires and cables with a cross-section of less than 16 square meters. millimeters. And during oxidation, this indicator decreases significantly and the area of the cable conducting current, in turn, also decreases. However, this should rather be considered a disadvantage.

Today, aluminum in electrical wiring is most often used in extensive power cables, where very important factor is the weight and cost of the material. The savings in this case can be very significant - aluminum is a cheap metal - and the amount of material used will still allow you to spend less compared to other types of wires. True Example This is due to its enormous popularity, the cores of which are made of aluminum. For aerial cable laying, this conductor is one of the most suitable. However, aluminum wiring has not been used in new buildings for a long time, and there are reasons for this.

Flaws

There are quite a few disadvantages to this type of wire:

fluidity of the metal (aluminum tends to stretch, this has negative consequence in case of screw connection of wires);
fragility of aluminum (in the process of aging and a long service life, the wires will simply break, especially with frequent loads and overheating).

All of these shortcomings are, to one degree or another, end result lead to the fragility of the entire power supply system and its short service life. When asked how long aluminum electrical wiring lasts, you will receive a comprehensive answer - a service life of up to 25 years.

A few important facts

So, to let you know why aluminum wiring is dangerous, we recommend that you familiarize yourself with the following facts:

In accordance with international standards Aluminum electrical wiring has long been recognized as a potential fire hazard.
Cases that have caused death have been recorded more than once.
In houses and apartments where an aluminum electrical network was used, fire cases were recorded 55 times more than with other electrical wiring.
This type of wiring is still permitted, but only on a temporary basis.
To prevent fire, do not connect copper and aluminum wiring together.

All these factors can cause a fire in the home network and, as a result, a fire in a house or apartment. You can clearly see how dangerous this type of electrical wiring is in the video below:

Example of a dangerous situation

Is it worth replacing the old wiring?

The answer to this question is unequivocal – Yes! One of the nuances that speak in favor of replacing aluminum wiring is the maximum load that it can withstand. Even 100% functional wiring, which was used before, in modern world will not withstand the load. And installing more powerful electrical wiring (with a larger cross-section) is prohibited, as this can lead to a fire.

Copper cable can withstand modern loads, is more reliable and fire resistant. Therefore, replacing aluminum wiring is certainly worthwhile. Especially if you choose the best option.

Another point that complicates the process may be the financial side of the issue. or an apartment can cost a pretty penny. Also, to completely replace the old wiring, it will be necessary to re-drill all living areas. If you are not a “jack of all trades” and cannot cope with the task yourself, in this case there is a way out - you can make a couple of separate lines with copper cable, so that they take on the main load of the electrical network, and the remaining aluminum lines are used only for lighting. In addition, new wires can be hidden under the baseboard or in the door jambs. Thus, you will reduce the load on aluminum wiring and make it safer and more reliable.

If you take on this labor-intensive process yourself, get ready for considerable expenses. Firstly, it is necessary. It’s good if you have one or your friends/relatives have one. Otherwise, it’s a waste again. Secondly, set aside time for this. In the modern world, even this can be difficult. And thirdly, be prepared for the fact that you may spend less time renovating than cleaning up after it.

But still there are life situations when complete or partial replacement of electrical wiring is impossible. In this case, it is necessary to know the most important rules on the use of aluminum wiring.

Basic operating requirements

If you nevertheless decide to use aluminum wiring in an apartment or private house, consider the following requirements:

Cross section of at least 16 square meters. mm (we already talked about this, but it wouldn’t hurt to remind you).
Use clamp contacts (as well as a special lubricant that will prevent contact oxidation and keep contact resistance low).
Use welding aluminum electrical wires in distribution boxes(requires a large investment of time and money, so it is rarely used). If you do not carry out the work yourself, monitor the work of electricians in your home and monitor the process to ensure that all technical aspects are adhered to.

It will also be useful for you to know the maximum load on aluminum wires different sections. We provided all the data in the table:

And remember, regardless of the type of wiring in your home, adhere to fire and electrical safety rules, as well as operating rules. This way you can protect your family and your home from unwanted consequences and accidents. Finally, we recommend watching another useful video

We are often asked the question: “What to do if the apartment has aluminum wiring?” In this article I will try to answer this question.

Aluminum wiring or copper?

According to the "Rules for Electrical Installations", aluminum wiring can be used in temporary buildings and structures, the service life does not exceed two years. In other cases, electrical wiring must be done with copper wires.

If we turn to statistical data, fires arising from faults in electrical wiring in electrical installations using aluminum wires occur 60% more often than in electrical installations using copper wires.

Additionally, I would like to note such a point as design load. The appearance of powerful household appliances in everyday life causes overloads of electrical wiring. If the wires in the apartment are made of aluminum with a cross-section of 2.5 sq. mm, then this wiring is designed for total consumption group line no more than 2.5 kW. Therefore, if you turn on a 2.7 kW kettle, and the lights are still on, the TV is on, etc., then we can definitely say that the wiring is overloaded. And this leads to its accelerated wear and tear.

That's why general recommendation will: if you are making repairs, then you should think about completely replacing the electrical wiring. And if the electricity in the apartment periodically goes out, then it may be worth changing the panel.

Service life of aluminum and copper wiring

As for the service life of wires, for aluminum wires the service life is approximately 10-15 years, for copper wires - 20-30. But you should also pay attention to the operating conditions of the wires. If wires are systematically overloaded, if the insulation is exposed to aggressive conditions external environment(rain, heat, frost, ultra-violet rays) then the service life is reduced.

Connection of copper and aluminum wiring

The main problem with connecting aluminum and copper wires is the formation of a galvanic couple by these metals. Which leads to oxidation of the junction of the wires. Therefore, it is necessary to exclude direct contact of these metals with each other. Connecting copper and aluminum wires can be done in three ways:

using special Wago terminals for connecting aluminum wires. The connections in these terminals are protected from oxidation special paste, which eliminates contact of aluminum with air. Direct contact of copper with aluminum is also excluded.
screw connection. It is imperative to exclude direct contact between copper and aluminum, as well as install special Grover washers, because This washer ensures constant pressure on the wires, otherwise the screw connection may deteriorate over time.
sleeves for connecting copper with aluminum, this method requires special equipment, and sleeves for such a connection cannot be bought in every store.

How to move aluminum wiring sockets

Rough electrical work refers to cables and their connections to each other. Rough electrical can be laid both on the surface and in the form hidden wiring, immured in the walls or floor. Finish electrics include all kinds of sockets and switches that are mounted exclusively on the surface.

The service life of electrical wiring is divided into nominal, actual and warranty.

Rated life

This is a combination of factors that ensure the working condition of the product. There are upper and lower limits for the rated life.

For example: NYM cable is used for installation of electrical wiring both in everyday life and in industry. Can be used both indoors and outdoors. The cable is designed for an operating voltage of 0.66 kV and can operate stably at temperatures from -50 to +50°C. Under these conditions, the cable has a service life of 30 years. However, the manufacturer provides a 5-year warranty. This means that if within 5 years the cable, while maintaining the nominal parameters in operation (0.66 kV at a temperature from -50 to +50°C), loses its functionality, then the manufacturer is obliged to ensure its replacement.

Warranty period

This is the time during which the company that manufactured the cable guarantees and ensures the preservation of the specified characteristics of the product. The manufacturer's warranty is valid only if the consumer fully complies with all rules for its transportation, storage, installation and operation. If the consumer violated the rules for using the cable (for example, allowed the cable to overheat to +70°C), then in this case the warranty will be canceled.

Actual service life

Depends solely on the consumer and is determined by how the product was handled. The actual period may either exceed or be less than that specified in the factory documentation for this product. The actual service life of the product is determined only by its technical condition.

The service life of clean electrical equipment (sockets, switches, cords, socket plugs) depends solely on the consumer and his careful handling of the equipment. As for rough electrical work (cable and its connections), the situation is completely different. The fact is that modern electrical panels with the help of automatic circuit breakers protect the line in such a way that any of the automatic circuit breakers (provided they are chosen correctly) will turn off much earlier than the cable not only burns out, but even begins to heat up.

For example: a cable with a cross-section of 2.5 mm can easily withstand a current of 20 to 25 amperes. At the same time, it is protected by an automatic circuit breaker of only 16 amperes. Thanks to this, the cable never heats up and therefore lasts almost forever. If a current of 80 amperes falls on such a cable, then it will naturally burn out. But such cases are extremely rare.

The warranty period for electrical wiring must be at least 10 years. If you, as a customer, are given a warranty of less than 10 years, then you definitely should not contact such “specialists”. Rough electrical installations must withstand at least five renovations and repairs. These updates are carried out every 5-7 years.

Thus, even under the most severe operating conditions, rough electrical equipment should last at least 50 years. After the nominal service life has expired, the network is re-tested under load. If, as a result of such testing, an electrical breakdown of the cable occurs, it is replaced. If the cable has withstood the load, then its operation continues. There are objects where old aluminum wiring has served for more than 70 years.

Modern cables in combination with spring terminals can work for at least 100 years without problems. Currently electrical cable tested on special test benches.

Test stands are mechanisms that simulate operation in conditions as close as possible to the real ones. Thanks to bench testing, it is possible in a very short time to fairly accurately predict what will happen to the cable after 10, 30, 50 and even 100 years of operation.

Test stands are designed for both cable testing and testing of its connections. The stands represent closed premises in which the cable is laid in walls, corrugations, and also simply in open connections. The cable is subjected to all kinds of stress. Such as may occur under conditions actual operation. These are current loads, temperature changes, and humidity changes. A cable that has passed all tests is subject to further use without the need to replace it.