Diagnostics of the electrical wiring of the apartment before buying

By acquiring property in the secondary market, we are always at risk. Two famous market fools from the saying - the seller and the buyer - are constantly trying to get the most out of the deal. Of course, the benefit is possible only at the expense of a vis-à-vis: the seller suddenly forgets about some of the shortcomings of the goods, and the buyer diligently knocks down the price, hoping to get a worthwhile item for nothing.

And the more expensive the acquired property, the sharper the hidden conflict of interests between the seller and the buyer, the more irresistible the desire to deceive the neighbor becomes and the higher the price of the error. Therefore, the situation becomes extremely extreme if the subject of bargaining is real estate.

For example, if an apartment is for sale, then the buyer does not have the opportunity to find out all its flaws for certain. Let's say summer is in the yard, and in winter it turns out that the heating radiators are slagged and do not heat at all. Or in a month it becomes clear that troubled rowdy neighbors live on the floor below.

Or it turns out that the electricity and / or water supply in this house is not stable. And we are not talking about cases where the seller’s ownership of the apartment is disputed by someone, and the transaction for its sale is declared invalid in the future. And this despite the fact that the buyer has already managed to pay the real, unquestioned money for housing.

Of course, all these problems, including even the last, are solvable. But resolving them requires time and money. Therefore, the buyer is interested to know in advance about the shortcomings of the purchased apartment in order to receive a discount that will compensate for future costs. These shortcomings may be related to the state of utilities, for example, electrical wiring.

Having some idea of ​​the technical side of the issue, it is possible to adequately assess the condition of the electrical wiring in the acquired apartment and avoid unpleasant surprises subsequently associated with its urgent replacement and repair.

Now we list the possible problems with the wiring that may be in the purchased apartment, as well as the signs by which these problems can be guessed in advance.

1. TN-C Grounding System

How to recognize?

This system is determined very easily: to each lamp, to each outlet and in general in the entire electrical network there are only two wires. These are phase and working neutral conductors.

BUT: the presence of a third, yellow-green protective earth conductor does not yet guarantee the TN-S or TN-C-S system approved by today's standards. After all, the third conductor can be connected to a working zero right in the opening apartment panel, or it can simply “hang in the air”.

To find out this circumstance, you will have to open the input shield and make sure that the working and protective neutral conductors come from different connecting buses, and the buses themselves are connected to independent long-distance trunk conductors. Armed with a multimeter, you can make sure that there is a voltage of 220 volts between the phase lead-in conductor and the protective earth bus.

What is fraught with?

The old TN-C system, which does not have a protective earth conductor, is not allowed for newly commissioned electrical installations. But for apartments in houses built before the change in technical standards (mid-90s of the last century), the operation of such a grounding system is allowed due to elementary hopelessness.

To transfer the entire housing stock to at least the TN-C-S system, substantial investment is required, and operating organizations simply cannot afford it.Therefore, people still live in apartments with an outdated grounding system. Well, of course, they sell such apartments to each other.

However, the TN-C system does not provide safety: the housings of household electrical appliances in it are not grounded, and the differential protection cannot work adequately. All this can theoretically lead to electric shock to residents.

But housing operation in the TN-C system is quite possible. Living in such an apartment will have to be careful: do not install outlets in the bathroom, turn off the washing machine and, if possible, other electrical appliances from the network for a period when they are not used. And despite these measures, one still has to occasionally endure painful electric shocks from the housings of household appliances.

The latter is due to the fact that all modern household equipment is designed for use as part of networks with a dedicated protective grounding conductor. This protective conductor in such devices is connected to the housing and is also used to operate the built-in surge protector. But if there is no protective conductor, then the housing becomes just a part of this filter and, thanks to the capacitors available in the filter, acquires an electric potential of 110 volts. In general, this potential does not pose a particular danger, but getting under it is rather painful.

It should be noted that during scheduled repairs of the electrical networks of residential buildings, the TN-C system is often replaced by TN-C-S by the efforts of operating organizations. But flatter yourself here is not worth it. First, in the end, the operating organization will still charge the cost of this modernization with the residents of the house. And secondly, to bring the network of your own apartment in line with TN-C-S standards you will have to do it yourself as a homeowner.

The operating organization carries out modernization only to the border of its responsibility, and this, as a rule, is the main driveway conductors (risers). Thus, the TN-C system in the acquired apartment is also an additional financial outlay in the future.

2. The poor condition of the conductors

How to recognize?

Actually, for a true assessment of the condition of the conductors, it is necessary to make electrical measurements and determine the degree of wear of the insulation. But for this it is necessary to perform measurements with a megger, which not everyone can do.

Therefore, it is better to focus on indirect signs. We open the opening shield, simultaneously assessing the state of the switching equipment. In the presence of differential protection, we test it for operability using the "Test" button. If the equipment is serviceable and does not work on the network, then the insulation of the conductors is in a decent condition.

But if the apartment is in an old building, then such delights as differential protection may simply be absent. But there may be such things as aluminum wiring in single insulation without color cores. And it is not that such wiring itself was subject to urgent replacement. But to expect problems with such wiring in the short term is quite possible.

What is fraught with?

Problems will result in increased leakage current. In reality, this can be estimated in the case of the installation of RCDs or difratomata. Such devices simply can not work as part of a worn electrical wiring. In the most advanced cases, due to leakage currents, simple circuit breakers that do not have differential protection can also operate.

It is also necessary to take into account the fact that the hidden aluminum old wiring also includes junction boxes, which are almost certainly hidden for a long time under numerous layers of plaster. However, the state of things in these boxes is of great importance.

Of course, often the wires in such boxes were tightly welded, wrapping the connection with electrical tape. Such a connection rarely fails, and you should not worry about it.But boxes are not so rare, the wires in which simply twisted without the use of any clamps.

Over the years of operation, such a connection of aluminum conductors is almost guaranteed to become unusable. Symptoms are the disturbed operation of electrical outlets, sparking and cracking in the box. All this can even lead to fire.

It is also necessary to take into account the fact that aluminum becomes very fragile over the years, easily breaks off when replacing sockets, switches, lamps and other fittings. That is, the owner of an apartment with an old aluminum wiring can almost at any time be faced with the need to at least partially replace this wiring itself.

Thus, the old aluminum wiring in single-layer insulation is fraught with the costs of its replacement and related cosmetic repairs, due to the fact that the wiring in apartments is usually hidden. This amount is considerable, and when bidding, the buyer is interested in taking it into account.

3. Worn wiring accessories

How to recognize?

The blackened and melted case of sockets or switches, junction boxes without covers, flickering lamps - all this eloquently suggests that the installation products have already worked out their time.

Perhaps this was due to overload. Perhaps the reason was the mismatch of the power of the lighting circuits with the current characteristics of the switch. Perhaps plugs and sockets of different standards were used. In general, all this is no longer important for the buyer of the apartment. The important thing is that there are problems and they will have to be addressed.

What is fraught with?

The solution, in fact, will not require special expenses, unless the new owner has Napoleonic plans to transfer or add sockets, switches or lamps. And the high qualification of the contractor will also not require the replacement of these products.

Moreover, delaying the replacement of worn wiring products is also not worth it. Sparkling and fused sockets and switches not only tremble nerves, but also quite logically can cause a fire.

4. Unsuitable composition of the opening shield, poor condition of the machines

How to recognize?

Obvious signs of the indecent state of automatic machines or other devices that are included in the shield are chips and cracks in the case, torn threads on clamping screws, traces of carbon deposits and fusion.

All this without any problems is solved by an elementary replacement. In the absence of any devices, you can add them and the maximum problem that you can encounter is the lack of space in the existing shield.

In this case, a new shield is acquired, into which all the equipment is transferred. We are talking about cases where, for example, there is no electric meter in the switchboard, or an introductory machine. Or if one of the lines is connected directly, without a group machine and, accordingly, overcurrent protection.

But more often there is another, more complicated situation: there is not only the necessary group machine, there is not even a wire itself for connecting the group. So, let's say, for a two-bedroom apartment there are only two group machines. We need to provide separate protection for the stove, for the bathroom sockets, for the kitchen sockets, for the sockets in the rooms and for the lighting network. Adding machines to the shield, you can’t solve the problem, because there are only two phase wires and two working zero wires.

What is fraught with?

Unfortunately, such a question is rarely resolved without major repairs of the wiring and replacement of the shield together with the electrical equipment. Afterwards, cosmetic repairs loom quite clearly for the reasons already mentioned above. Total costs are more than impressive: during the bidding, the buyer must definitely remind the seller.

It is impossible to leave the shield incomplete or with faulty equipment in any way.Such a shield is only the appearance of protection and will let you down at the most inopportune moment, by setting up a fire or by shocking someone with an electric shock.

5. Lack of an additional potential equalization system

How to recognize?

Almost all apartments in houses of the old construction sin this. This is understandable: in the TN-C system in the input panel there is no main PE grounding bus to which all protective neutral conductors must be connected. Accordingly, there is no protective conductor in the bathroom, to which metal pipelines, a ventilation casing, a metal bath should be connected ... in general, all the metal in the bathroom.

All these elements must be connected electrically in a common junction box of an additional potential equalization system (DCES). If there is no such connection and there is no box, then no, of course, and DCS.

What is fraught with?

The potential equalization system requires the installation of its own conductor and box just so that all the conductive elements in the bathroom are always under one common electric potential, and there is no voltage between them. Thus, touching at the same time, for example, a bathtub and a water pipe, a person will not be able to find himself even under minimal stress. This is very important for the bathroom as a room with an increased risk of electric shock.

If the house in which the apartment is purchased is connected to the TN-C-S or TN-S network, but the apartment does not have a control room, then it is better for the new owner to work hard and carry out work on installing the box and installing protective conductors for this system.

Well, if we are dealing with a TN-C system, it is better to simply electrically combine all the metal elements in the bathroom, giving them a common electric potential using the same protective conductors and boxes. But then electrical equipment cannot be included in this system for safety reasons.

Neglect of the DCAP simply leads to the danger of electric shock in the bathroom.

See also:What to do if the machine works in the electrical panel