Replacing electrical wiring in an old two-room apartment

Most of the apartment buildings from the Soviet era have a network capacity that is not designed for modern electrical appliances. Old wiring in apartments wears out, causing short circuits and fires. Often, do-it-yourself wiring replacement in Khrushchev coincides with a major overhaul. Before starting work, it is worth considering replacement options, technical requirements, choosing an installation method and calculating the power of the network.

Full and partial replacement

According to the standards, until 1991, the flap of the apartment was supposed to have a power of 3.5 kW. In modern conditions, various electrical appliances are used, so the power is no longer enough. There are two ways to change the electrical network.

Features and cons of partial replacement

Complete replacement of hidden electrical wiring in a Khrushchev apartment is accompanied by noise, which can interfere with the peace of mind of neighbors. The laboriousness of work to extract the cable from all walls is within the power of a few owners. If the Soviet aluminum wire is in good condition, you can partially replace the communications. In the process, it is important to take into account the following points:

• a new automatic input for 7 kW is installed to protect against short circuits and de-energizing premises;
• sockets designed for a load of 10-15 A must be grounded;
• for laying, an insulated copper wire with a current holding of 2 to 5 A per mm2 is used.

  

The disadvantages of partial replacement include the electrochemical incompatibility of copper and aluminum wires, the inconsistency of the cable cross-section with the power of modern household appliances. Small old boxes often run out of space, and rewiring brittle aluminum cables requires skill.

Partially only open lines should be replaced.

When a complete replacement is required

Overhaul with the dismantling of the flooring, cardinal alteration of the walls provides for the complete replacement of communications. It is necessary to completely change the wiring in the following cases:

• when household appliances are turned on at a time, a burning smell appears;
• sockets spark when appliances are turned on;
• some outlets have no power;
• there is a leakage of current through the wall;
• wires break, become less flexible.

Complete replacement of electrical wiring is carried out once every 20-25 years.

Problems with old houses

The construction of the Khrushchev buildings took place in 1958-1985. within the framework of urbanization. The power lines in them differ depending on the series of buildings:

• Buildings from the period 1963 - the places for the junction box, gates, wire connections were left to the discretion of the electrician;
• Panel houses of 1965 - wire routing and concealed laying were carried out in the channels of panel slabs;
• High-rise buildings of 1974 - refer to a typical building according to the requirements of the Unified Catalog of Building Parts.Due to the poor quality of the channels in the slabs, the wiring was laid in niches under the floor of the upper floors, leading the cables through the through-gates of the ceiling.

In the 60s - 70s. did not expect such a number of electrical appliances, so the network withstood a maximum load of 3.5 kW. The total power of a modern kettle and iron is 4 kW.

The wiring diagram in a two-room standard layout in Khrushchev included several lamps, an iron, and a radio receiver. The aluminum cable, popular in the days of Khrushchev, also had disadvantages:

• broke over time with slight bends;
• required a complete replacement once every 20 years;
• under voltage, it was subjected to electrocorrosion, which became the cause of fires.

In 1960-1980. it was customary to ground the power line according to the scheme with a solidly grounded neutral. At the end of the twentieth century, the TN-C-S scheme was adopted in the Russian Federation, to which the Khrushchevs did not correspond.

Strands of wires and bare sections due to the application of the branching method provide for a complete replacement of the aluminum cable with a copper one.

Where to start replacing electrical wiring

At the preparatory stage, a plan is drawn up for a new wiring in a two-room apartment. It is coordinated in the BTI and Energosbyt. Preparation also includes:

1. Visual inspection of the line for visible damage.
2. Drawing up a drawing with the electrical systems of the whole house.
3. Purchase of consumables - sockets, cables, switches, boxes.
4. Search for the necessary tools - punch, grinder, indicator, side cutters, level, flashlight, assembly knife, pliers, soldering iron, fabric tape.

Buy a wire with allowances after measuring the length of the route.

Power calculation

It is necessary to replace the electrician so that further failures and overvoltage of the network do not occur. The line power is selected taking into account all electrical equipment and depends on the cable cross-section. You will need to make several calculations:

1. Summarize the capacities of all equipment connected to the power grid.
2. Add +100 watts to each fixture.
3. Divide total by 220.

If the result is 12-15, a cable with a cross section of 1.5 mm2 is allowed. For an apartment of a standard layout, this is enough.

When there is a large load on the line, it is allowed to increase the cable cross-section, equip communications in a two-wire or three-wire circuit.

There are risks of failure when using thick wire.

Apartment power plan

In old houses, there is an electrical switchboard on each floor, where there is a meter, a packet switch, and circuit breakers. Therefore, when a wiring diagram is designed in a two-room apartment, it is worth making an independent power and lighting circuit, planning the main and additional branches. In Khrushchev, it is allowed to use the following connection options:

• Parallel - energy is supplied to the consumer from a power source through its own line. A three-core cable is connected to a single-phase device, a five-core cable with wires of phases A, B, C, zero and earth to the three-phase device. Such a scheme provides for the organization of its own line for each consumer and the installation of an individual RCD.
• Serial - a cable is pulled from one power source, and the consumer is connected to it at a certain distance. To implement the scheme, you will need a wire with a large cross-section and grooves in the walls. The source of energy will be a generator with a rating of 220 V. To save money, you can stretch an electric cable from the panel to a specific consumer.
• Series-parallel - the scheme is used in most apartments. The distribution box is designed for consumers grouped by type (boiler, sockets, light) or location (kitchen, bedroom, bathroom).

Serial-parallel connection is the best option for budgetary complete replacement of the power grid.

Features of installation in Khrushchev

The scheme of the selected wiring for laying a standard two-room layout in Khrushchev is based on consumer groups. These include lighting devices, household and power outlets, a bathroom and a corridor. The arrangement is carried out using two technologies.

Hidden way

In brick or panel houses, it is allowed to lay wires in three ways:

• Inside the ceiling - the route from the switchboard goes vertically, runs along the strobes or in the corrugation. Indoor ceiling tiles already have channels from where power cables can be pulled to lamps, switches, sockets. The wiring runs perpendicularly, without dropping horizontally below 15 cm. Each switch box has an individual automatic machine.
• Under the plaster - wires are inserted into pre-drilled holes, fixed, and taken out to consumers. The lines are masked with a layer of plaster to prevent damage from voltage fluctuations.
• Under the floor - the line is drawn under the floor surface. Channel-pipes are laid, which are then filled with mortar. Lines for sockets and lighting are masked with a mounting box or pipe.

With a combined connection, pipes and cables are distributed at an acute angle. The routes are connected by means of a junction box with an input shield.

Open way

The open version is used when it is impossible to organize the electrical network in another way. There are several methods:

• On the brackets - copper wires with a cross section of 2.5 mm2 are needed for sockets, for lighting - 1.5 mm2. Metal strips are used as brackets, fixing them so that the non-combustible part extends 1 cm beyond the line.
• In pipes - corrugated flexible products exclude surface leveling. The pipe diameter is equal to the total thickness of the conductors multiplied by 2. Fastening is done with screws, clips, dowels and nails. Each element is removed from each other by 20-40 cm.
• In boxes - a metal or plastic cable channel and the plinth is equipped with a removable latch-on cover. The main difficulty of the work is the correct fastening to screws, dowels or staples. The sockets can be mounted directly on the box.

If the apartment has a retro interior, the wires need not be masked.

What tools will be needed

Self-replacement of electrical wiring is carried out using the following tools:

• puncher;
• drill for concrete, drill for concrete (16-20 mm), core drill (90-100 mm);
• chisel 25-30 mm;
• soldering iron 40 W;
• grinder with a disc for stone;
• screwdrivers;
• pliers;
• side cutters;
• phase indicator;
• tester;
• cord and level;
• flashlight;
• stationery knife;
• putty knife.

Before work, it is important to calculate the number of wires - measure the segment from the shield to the connection point, taking into account protrusions, niches and corners.

Instructions for replacing wiring

At the preparatory stage, it is required to conduct a visual inspection and check the quality of the connection. Further operations are performed according to an algorithm developed by professional electricians.

De-energizing

To gain access to the system and not get an electric shock, you will need:

1. Turn off the main machine, from which the cables go to the apartment.
2. Check for voltage.
3. De-energize each wire, having previously checked it with a phase indicator.
4. Test switches and sockets for voltage.

Old wiring without damage can be left in place.

Dismantling old wires

The electrical wiring is dismantled after a complete shutdown of electricity. This can be checked with a multimeter.

First, local dismantling is performed from the distribution box under the ceiling. It is opened, the lead-in cable is found and removed.If the wire does not stretch, it is cut further and then insulated. Further work is carried out in a similar way.

Surface preparation

Wall slitting is possible horizontally or vertically.

1. Marking the points of the location of the socket boxes according to the drawings.
2. Marking of places for sockets with the possibility of masking the cord.
3. Accurate definition of the boundaries of the channels with a perforator.
4. Manual hole alignment with a chisel.
5. Performing an oblique cut with a grinder for an even location of the wire.
6. Punching holes in a brick wall with a crown fitted on a hammer drill.

Curved grooves often cause cable breaks and fires.

Grounding the line

Installation of a protective line in buildings of the period 1960-1980. was not provided. To solve the question of where to get grounding in Khrushchev, you will need to make a zeroing:

1. Connect the ground pin in the socket to zero.
2. Bring the structure to the outside of the shield.

The connection, in which the input circuit breaker switches on "zero" at the moment of the current protection operation, is prohibited by the regulations.

Installation

The installation of a new power line is carried out in stages:

1. Installation of socket outlets on alabaster in the holes.
2. Cutting the cable and corrugated pipe to the required length.
3. Pulling the wire inside the corrugation on a flat surface.
4. Laying the corrugation in the groove with the winding of the cable ends in the socket.
5. Align the hole to the wall line.
6. Putting the grooves in small pieces, every 50 cm.
7. Plant the second end of the corrugation on the input shield.
8. Processing the ends of the wires with paste, fastening with a clamp and fixing on the shield protection terminal.

Lead the apartment wiring into the shield by weight.

Checking and plastering

Testing of the finished system is carried out as follows:

1. Electricity is turned off, current is supplied.
2. Each branch of the cable is checked with a tester for a short circuit. For this, the indicator is zero and phase.
3. Lead wires to the corresponding terminals.
4. Retest for short circuit.
5. Turning on the main machine, supplying electricity.

Be sure to see how lamps, switches, sockets work.

At the last stage, a primer is applied to the surface of the wall, then a layer of plaster and finishing.

Self-replacement of the electric line in Khrushchev is complicated by old wires, an incomprehensible connection diagram, and a lack of grounding. For this reason, it is worth adhering to the exact sequence of work, drawing up detailed drawings and consulting with specialists.