Piercing walls, or a little about the passage of cables through building structures

When installing electrical wiring and cable lines, you often have to solve the problem of how to route a wire or cable through the external walls of buildings and internal partitions. There are many requirements for the passage of electrical conductors through obstacles, and it is very important to comply with each of them, because this affects not only the ease of repair and replacement of wiring, but also the safety of its use. In this article we will tell you how to lay cables through a wall made of wood, brick and concrete in accordance with the requirements of regulatory documents.

Regulatory documents for laying

The wiring of electrical cables through walls must be carried out in compliance with the requirements of two regulatory documents:

1. Rules for the construction of electrical installations (PUE) are one of the main sets of laws in the electric power industry. This book is “sacred” for electricians. She explains in as much detail as possible what equipment is installed where and how correctly.
2. SNiP 3.05.06-85 (in clause 3.18) (building codes and regulations) - considers the principles that should be taken into account when constructing buildings and laying electrical communications and cables in them.

Rules for electrical installations
In addition, installation rules can be found in the Federal Law of June 22, 2008 - “Technical Regulations on Fire Safety Requirements.” Article 82 of this document describes the standards.

Any major electrical work, especially when installing cables in a new building, is carried out in accordance with plans, drawings and various design documentation. Without compliance with this requirement, the building will not be accepted for operation.

Filling the Passage

As you can see, regulatory documents operate in terms of “fire resistance limit of a structure” and this conceals a key nuance regarding the passage of cables.

If our wall does not have a standardized fire resistance limit, then PUE clause 2.1.58 and SP 76.13330.2016 clause 6.4.1.25 are slightly different in the interpretation of filling: PUE requires in any case to be sealed with fireproof material, but SP allows not to seal it. However, it “admits”: who needs extra holes - only mice and those who like to eavesdrop on what’s going on in the next office.

A small nuance: the PUE uses the term “fireproof”, which is absent in modern regulatory documentation, however, SNiP 2.01.02-85* (replaced by the muddy SP 112.13330.2011) has the definition “1.4. Building materials according to flammability (flammability) are divided into three groups: non-combustible (non-combustible), slow-burning (difficult to burn) and combustible (combustible).” Those. non-combustible materials are needed, and all installation “fireproof” and “fireproof” foams belong to group G1 - low-flammability.

Let's move on to structures that have a standardized fire resistance limit. If possible, this information should be obtained from the developer of fire protection systems or try to obtain from architects.

Usually in old administrative buildings it is impossible to obtain such documentation, for example, when work is only carried out on cosmetic repairs of existing premises of a couple of floors or the laying of communication networks.

The following is a simplified diagram that is not a “silver bullet”.

We determine structures with a standardized fire resistance limit:

If there are unfilled openings in the wall (for example, it is not brought to the ceiling above the level of the false ceiling or “stands” on the false floor), the thickness of the wall is one sheet of plywood - we do not have a wall in the fire protection sense and the fire resistance of such a structure is not standardized (I have seen server rooms with such walls).

Next, you need to determine the normalized fire resistance limit of such structures. With the help of the federal law “Technical Regulations on Fire Safety Requirements” dated July 22, 2008 N 123-FZ, we determine the functional hazard class of the building (type - FH.H). If our building contains several functional hazard classes, then we consider that there are fire barriers of type 1 between them. Then we find out what degree of fire resistance our building has and use tables 21 and 23 to determine the limits (this should be relatively easy for an engineer).

It is worth noting that all “dedicated” technical rooms must have a fire resistance of at least EI45/REI45; this can be achieved, for example, by using a half-brick brick wall (at least 65 mm thick) or a plasterboard partition of type C111, according to standard Knauf solutions ( in offices, partitions are usually made of type C112 with fire resistance EI60, but as the architects explained to me, this is to comply with noise standards).

If we cannot determine whether a wall has normalized fire resistance or not, we assume that it has normalized fire resistance.

GOST R 53310-2009 Cable penetrations, sealed entries and busbar penetrations. Fire safety requirements. Fire resistance test methods

3.1 cable penetration : A structural element, product or prefabricated structure intended for sealing the passage of cables through enclosing structures with rated fire resistance limits or fire barriers and preventing the spread of fire into adjacent rooms within a rated time. Cable penetration includes cables, embedded parts (ducts, trays, pipes, etc.), sealing materials and prefabricated or structural elements.

There is a small nuance for cable penetrations: they should not reduce the fire resistance limit of the structure, while filling door and window openings have weaker requirements.

The time has come to choose how and what to seal. There are many solutions on the market, but before using them, we be sure to check for a certificate in accordance with GOST R 53310-2009 (one-component “fire-fighting” foam usually has a certificate only in accordance with GOST 30247, which is not suitable for solving our problem).

The principle of operation for all penetrations is approximately the same - a fire-resistant material is used (burns slowly), which, when exposed to temperature, expands and closes all cavities.

When choosing a filling solution, it is important to pay attention to the thickness of the structure into which the cable penetration is installed.

Basic principles of electrical cable installation

PUEs are written in complex technical language. If we simplify the points that tell us how to pass a cable through walls, we can highlight the following basic rules:

1. Electrical wiring must be replaceable. This requirement is described in paragraph 2.1.58 (talking about the 7th edition). The ability to replace cables is necessary to repair or modernize existing electrical networks. For example, if during the construction of a residential building, grounding was not taken into account in the design, but now it is necessary to replace the old cable with a new one, which contains separate PE and N conductors.
2. Cables must be protected from environmental influences and mechanical damage. This is done using various non-flammable trays, cable ducts, electrical skirting boards, metal or plastic corrugated tubes. Such protection saves the cable from moisture and dirt from the outside and prevents it from burning.
3. The holes through which the cable passes through the walls are sealed (covered) with moisture-resistant, non-flammable materials. This plug should be easy to remove when replacing wiring.

Running cable through the wall

Cables in the wall of a residential building

To install the wire in the wall, you will need to drill a hole. It’s easier to do this with a hammer drill switched to drilling mode. The main thing is not to damage the cables already in the wall with the drill. Ideally, a hidden wiring detector is used to detect them. Prices for this device start at about 1000 rubles. It is not advisable to purchase it for drilling one hole. To find cables, you can try cheaper methods:

1. Logical. No equipment needed. It is important to understand that the wires in the wall run near the outlets and switches. Usually from the side or from above, less often - diagonally.
2. Using an indicator screwdriver. What you need is a transistor one, into which 3 button batteries are inserted. It costs a penny and is sold in any store from the “thousand little things”, “everything for the home” series, etc. An indicator screwdriver can feel the cable in the wall at a depth of 10-15 mm. Application requires practice.
3. Some radio-based devices are capable of sensing electromagnetic fields from wires carrying current. These include radios, hearing aids or walkie-talkies. The method is dubious, but sometimes it works.

Device for detecting wiring in the wall

Installation tools

For drilling you will need at least a hammer drill with a drill. If the hole in the wall has a large diameter, then a hammer with a pick or chisel will also come in handy. The cable penetrations themselves through the walls are easiest to make in a metal or PVC pipe. During work, dust from concrete and plaster is generated. It should be removed with a special construction vacuum cleaner, because a simple household vacuum cleaner will not last long in this mode of operation.

Once the wire is installed, you will need a putty knife to seal any remaining voids. A tool for cutting pipes, measuring and applying markings to the wall will also be useful.

Hammer with drill for drilling holes

In what cases are sleeves used when cables pass through walls?

Hello, can you tell me in what cases are sleeves used when passing cables through walls?

In all cases, when cables are laid behind impenetrable suspended ceilings or pass through partitions with flammability group G2-G4, they must be laid in steel pipes or blind steel boxes with localization capability.

Can you tell me what standard technical documentation is written in it?

Do you need a sleeve when passing a metal grounding strip through a wall?

PUE, clause 2.1.58. In places where wires and cables pass through walls, interfloor ceilings or where they exit outside, it is necessary to ensure the possibility of changing electrical wiring. To do this, the passage must be made in a pipe, box, opening, etc. In order to prevent the penetration and accumulation of water and the spread of fire in places of passage through walls, ceilings or exits to the outside, gaps between wires, cables and pipes (ducts, openings, etc.), as well as backup pipes (ducts, openings, etc.) should be sealed. .p.) easily removed mass from fireproof material. The seal must allow replacement, additional installation of new wires and cables and ensure the fire resistance limit of the opening is not less than the fire resistance limit of the wall (floor).

clause 2.1.79. Entries into buildings are recommended to be made through walls in insulating pipes so that water cannot accumulate in the passage and penetrate into the building.

Source

Procedure for making cable holes

The technology for making a through hole greatly depends on the wall material. This criterion affects the tool used and the complexity of the work. The material of the wall also determines the degree of fire safety of the wiring.

Wall in a panel, brick or monolithic house

Making holes in concrete or brick is harmful to human health. Dust particles clog the respiratory tract, enter the lungs and the mucous membranes of the eyes. It is advisable to worry about safety in advance and carry out such work in protective glasses and a mask (at least a medical one).

The holes are made with a hammer drill and a drill. It is designed specifically for such work. In the front part of the drill there is a carbide tipped from Pobedite. It's important to be careful. If during the drilling process it gets into the wall reinforcement, then there is a high risk that the solder will fall off and the drill will have to be thrown away.

Pobedite nozzle for drilling holes in concrete

To carry out the work you need:

1. Make sure the frequency of the drill mounting part is correct. There should be no dust on it from previous work. It can get into the hammer drill chuck and damage it. You can get rid of dust using any rag, napkin, etc.
2. Install the drill bit into the hammer drill chuck. Even a properly secured drill will dangle along its axis by 10-20 mm. This is fine.
3. Turn the tool into drilling mode. The corresponding switch is usually located on the side of the hammer drill.
4. Let it run for 10-60 seconds in idle mode. This is necessary to make sure that the hammer drill is working properly, that is, whether the engine sound is normal, whether there is any heating, whether there is smoke or a burning smell coming from the tool.
5. Then you can start drilling the hole. Don't be distracted while working. The hammer drill must be held firmly. Periodically, the drill bit should be partially removed from the wall to help remove concrete particles. It is not necessary to stop the rotation.

Plasterboard wall

In terms of safety, everything is the same as when drilling concrete or brick. That is, the eyes, respiratory organs and mucous membranes are protected from dust.

Drywall is easy to process. The hole can even be made with a nail or knife. Actually, this is what they do if they need a couple of holes, but there is no suitable tool at hand. But it is much more correct to carry out penetrations using a drill and a regular drill. Its diameter should be slightly larger than the thickness of the wire.

In rare cases, it becomes necessary to run a large-section power cable through drywall. Here you will have to use a plaster drilling crown or a feather drill.

Hole for cable in plasterboard wall

In any case, it is important to consider a few simple rules:

1. Make sure that the drilling point does not coincide with the supporting profile or another cable.
2. The wire is laid in sleeves made of non-flammable PVC pipe or corrugated tube.
3. If there is a sealant (foam plastic, mineral wool) between the plaster sheets, then it should be pierced with any long thin object. For example, a piece of reinforcement, a drill or a screwdriver.

Wall made of wood or chipboard

Many people are familiar with making holes in wood from school. You should be careful not to catch a splinter. It is advisable to avoid overheating the wood with a dull drill, as smoldering sawdust can fall where it is not needed and start a fire.

The drilling itself is done with a drill and a wood drill. It should be sharp. This will make the process much easier and faster. The drill for metal is not suitable. It will, of course, make a hole, but the work will be long and hard.

Laying wire through a log wall
The nuances of the work are as follows:

1. When passing through a wooden partition, knots should be avoided if possible. These areas are extremely hard and therefore inconvenient to work with. Also, knots can simply fall off from the general layer of wood.
2. Cracks can also create problems. You should avoid them, because there is a risk that the board will split.
3. You need to make sure that there are no wiring, water pipes or metal structural elements on the other side of the wall.
4. Wood catches fire easily when heated. Therefore, the cable passes through the wall in a plastic pipe, cable duct or corrugation. It is unacceptable for electrical components (including insulated ones) to come into contact with wood. Especially at the point where the cable passes through the wall, because there will be nowhere for the generated heat to be removed.

Pass execution

You can see that various passage options are allowed: both in pieces of pipes and simply through the frame. The mandatory presence of sleeves is not required anywhere, and the term “sleeve” itself is not used. The main thing is not to damage the cable sheath when pulling and ensure the replacement of the wiring. The simplest solution is pipe sections, but you can also make a neat hole, plaster it and, if necessary, reinforce it. The use of corrugated pipes is possible only if they are not filled (to ensure replacement).

Types of fire penetrations

Professional cable penetrations are used for the electrification of modern buildings. They are more suitable for input power cables with a cross-section of 25 mm2 and above. It is convenient to use a table to describe and compare them.

The use of cable gaskets improves fire safety. At the same time, sealing of the holes through which the wire is inserted is achieved. This prevents the spread of fire and smoke between adjacent rooms, which can save someone’s life in an emergency.

Conductor products are mounted on walls made of various materials. Some of them are more flammable, and some are the opposite. This factor must be taken into account when designing and constructing electrical networks of a building.

Aluminum sleeve for crimping

Previously, the most accessible way to connect wires was twisting. Twisting was used everywhere. Moreover, regardless of whether the wires were aluminum or copper. Although, to tell the truth, copper was used in few places. But progress, as they say, does not stand still, and today many ways of connecting wires are already known.

Flexible sealing with stuffing box

Packing gland
The body of this gland does not have a flanged pressure fitting. A thrust ring and two collars are installed inside the housing. A packing of tarred hemp strands is placed between the thrust ring and the collar. The ends of the seal are caulked with asbestos-cement mass and sealed with bitumen mastic. Such seals are used in low-moisture soils. In dry soils, tow and rags can be used as padding.

Pressure seals are produced according to the standard series 5.900-2