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When reconstructing wiring or installing a new one, it is recommended to “pack” it in a protective sheath. Most often, corrugated electrical pipes are used, which are usually called “corrugations for cables and wires.” It is a round hose with a ribbed surface. Due to the ribbing, its flexibility is significantly increased.
Why do you need a corrugation
The laying of electrical cables and wires in the corrugation is recommended for various reasons:
- When laying in combustible walls (wooden or frame), behind combustible finishes (lining, PVC boards), when attaching to wooden floors – for reasons of fire safety. In this case, non-combustible casings are chosen.
- When laying behind finishing materials – behind lining, drywall, PVC boards, etc. – for security reasons. To make it harder to damage the cable when trying to hang something on the wall. In this case, the most important indicator is the hardness of the shell.
Corrugated pipes for electrical wiring come in different colors. It’s not easy, colors have a certain meaning. - When laying the cable in a screed or under the floor, for finishing, the corrugation is used for several purposes. Firstly, to protect against squeezing when pouring concrete. Secondly, to be able to change the cable in case of damage without destroying the floor. Third, to protect against damage.
- For outdoor laying, the sheath is needed to protect the cable from atmospheric influences (ultraviolet) and mechanical damage.
- With open laying through the air, a corrugation with a wide temperature range (to withstand heat and frost) and resistance is required. to ultraviolet. If the cable is suspended, reinforcement is also needed to increase the load-bearing capacity.
- When laying underground, water tightness is important, as well as rigidity.
When laying a rigid corrugation on turns, it is better to use special couplings
In general, corrugations, even metal ones, are not the best protection against mechanical destruction. One can only hope that, having felt that the drill has failed, it will be possible to stop in time. And in order not to get into the electrical wiring, it is better to have an exact plan for laying it with measurements and binding to the corners. After all, a cable in a corrugation, even under load, is not determined by every wiring detector. So do not forget before pouring the screed, before finishing, take pictures, sketch the distances.
Types of corrugations for laying cables
The corrugation for the cable is different in strength:
- Light. It has a thin wall and the highest degree of flexibility. Recommended for laying under cladding in walls and ceilings. Holds mechanical load weakly.
- Average. Slightly thicker than light, but not as stiff as heavy. Can be used in walls and screed. They are good in the walls, but it is better to lay heavy corrugation in the screed.
This is a double-walled corrugation – ribbed on the outside, smooth on the inside. With it, re-tightening the cable is not a problem. - Heavy. The walls are thick, flexibility is low. Can be laid in a screed, buried in the ground. For turns, it is better to use corners or special couplings, since the minimum bending radius is quite large. They give a normal degree of protection both in terms of moisture and dust resistance.
- Reinforced. Plastic sheaths are applied over the steel wire twisted into a spiral. This is the best option for laying in the ground and for hanging.
As you can see, the classification is based on strength properties, which determines the area of uXNUMXbuXNUMXbuse.
Varieties
In addition to all this, there is also a corrugation with and without broach. A broach is a thin cable or wire that facilitates pulling the cable into the corrugation. The cable is tied to the end of the cable, pulled by its other end, tucking the cable inward. It is problematic to cope with this task without a broach – with sufficient rigidity, you can simply put a few meters of cable inside, but if the route is long, it will be too difficult.
If we talk about the types of plastic corrugations, it should be mentioned that there is a two-layer corrugation. Outside, it has the same ribbed surface, but inside it is smooth. Corrugation for this type of cable is expensive, but if necessary, you can really stretch a new cable into it. In those types where the inner wall is ribbed, this is far from always possible – if the track has a minimum of turns, and even those along a wide radius.
Metal corrugation for cables is also different. It is made from galvanized or stainless steel. In addition, there is a metal corrugation with a polymer coating. It has the best characteristics for protection against dust, moisture ingress. Such a protective shell is also called metal-polymer.
What materials
Corrugation for cable and electrical wires is made of plastic and metal. The materials used are different, with different characteristics. They must be selected based on the tasks that they must perform.
- Polypropylene (PPR). The color of this corrugation is usually blue, the material is self-extinguishing, does not support combustion. Differs in the increased water resistance can be used for laying cables on the street or in rooms with the increased humidity.
- PVC (polyvinyl chloride). By color – gray pipes, self-extinguishing. PVC corrugation is not waterproof, it can only be used in dry rooms.
Black cable corrugation is most often made of HDPE, but it can also be made of polypropylene (PPR) - HDPE (low pressure polyethylene). The color is orange, black, the material is combustible, but resistant to chemical attack and water. Scope – laying in screed and strobes in non-combustible walls, open laying on the street.
- Metal (stainless or galvanized steel). Non-combustible material, resistant to mechanical and chemical influences. Recommended for electrical wiring in combustible buildings (wooden, frame). Also good for laying outdoors.
If we talk about compliance with fire safety standards when installing gaskets in combustible walls, a metal pipe is ideal. It saves from the loads that may arise when changing the size of the building. Rodents cannot cope with it either. It is also the best option in terms of fire safety: even if short-circuit currents occur and the circuit breaker fails, the probability of burning a pipe with a wall thickness of 2 mm is very small. So the fire won’t start. If laying electrical cables in pipes does not appeal to you at all, then you can use metal cable channels or stainless steel or galvanized corrugations.
Corrugation for cable, dimensions, prices
Corrugated pipes for electrical networks are available in sizes from 16 mm to 65 mm. When choosing a size, it should be borne in mind that these products have two diameters – outer and inner. If you are going to lay several conductors – wires or cables – the diameter must be selected so that there is a gap of at least half the radius. This requirement is based on the fact that with group laying (it is necessary, by the way, to take a special cable), it will heat up more and the presence of an air gap will contribute to better heat dissipation.
Size selection
The choice of corrugation diameter also depends on the area where it will be laid:
- to lighting fixtures – 16 mm;
- to sockets and switches – at least 20 mm;
The size of the corrugation for an electric cable is selected depending on the number and size of conductors - from the main junction box to the next box, from the shield – at least 25 mm;
- the connection between two electrical panels is at least 32 mm, and it is better to have a spare second line;
- passage through the floor overlap – with a rigid corrugation of at least 40 mm in diameter;
- laying low-current cables (telephone, internet, antenna, etc.) – from 25 mm.
The diameter of the corrugation for laying the cable is selected depending on the number and cross section of the wires. Data for copper conductors are given in the table.
This information is for reference, but you can navigate it. You can take a larger, but not a smaller diameter.
Prices
Generally speaking, the cheapest is corrugation for PVC cable, in the middle range – PP and HDPE, the most expensive of all – metal corrugated. Moreover, the option with broach is slightly more expensive than without it. When buying, you need to pay attention to the same wall thickness, to the uniformity of color.
Corrugation for cable is sold in coils of 50 and 100 meters, less often it can be found in meters, but then the price is slightly higher. In general, the price depends not only on the material, but also on the wall thickness. The cheapest is light PVC corrugation for cable, but sometimes it looks more like just a film. From what it can protect, it is difficult to say. If you are concerned about quality, it is better to purchase everything related to electrics not in construction supermarkets such as Leroy, etc. and in specialized ones. The quality there is usually better, and the prices, if higher, are justified. In order for you to have an idea about the possible spread of prices, in the table we will summarize several types of corrugations with a brief technical description.
| Name | A type | External diameter | Inner diameter | Broach | Price per meter | IP | appointment |
|---|---|---|---|---|---|---|---|
| PVC corrugation | easy | 16 mm | 11,4 mm | Yes | 2,4 rub | ||
| Corrugated HDPE pipe black | DKS | 15,7 mm | 11,3 mm | Yes | from 7,5 rub / m | 55 | for concealed laying |
| Corrugated HDPE pipe black | DKS | 19,5 mm | 14,5 mm | Yes | from 8,9 rub / m | 55 | for concealed wiring |
| Pipe HDPE red double-walled | tough | 50 mm | 41,5 mm | Yes | 78,5 rub / m | 44 | for concealed laying |
| Heavy HDPE pipe | Heavy | 31 mm | 23,4 mm | Yes | from 9,7 rub / m | 55 | hidden gasket |
| Pipe PPL (polypropylene) corrugated | easy | 19,7 mm | 14,8 mm | Yes | from 28 rub / m | 55 | open, concealed gasket |
| Polyamide corrugated pipe | black | 21,2 mm | 16,8 mm | no | from 52 rub / m | 68 | open, concealed laying, UV resistant |
| Polyamide corrugated pipe | gray | 21,2 mm | 16,8 mm | Yes | from 48 rub / m | 68 | open, hidden gasket |
Installation of corrugated pipe
For outdoor (open) installation, special plastic clips are used to fasten the corrugations for cables and wires, which are selected according to the outer diameter of the pipe. Clips are fixed after 20-30 cm on self-tapping screws or dowels – depending on the type of wall. A corrugation for the kbale is inserted into the installed clips, pressed until it clicks. When mounted in a strobe, it is fixed with plastic ties or dowel-ties. You can also use homemade fasteners – tin strips with nails or screws in the middle.
When developing a route, the following recommendations should be taken into account. They proceed from the fact that the route should be without sharp turns – in order, if necessary, to tighten a new piece of cable. Because:
- The maximum possible length of the section is 20-25 meters. Provided that the track has no more than 4 turns.
Lay the electric corrugation in parallel, trying to make as few turns as possible - Turns should not be adjacent. The distance between them is at least 4-5 meters. If there is a need to make turns nearby, it is better to put a junction box or an inspection hatch near them.
- The angle of rotation is at least 90°, the radius is larger, the better.
- If the routes for electrical wiring and low-voltage cables and wires go side by side, the minimum distance for laying two corrugation sleeves is 200 mm. They can only intersect at right angles.
These rules relate to the development of a route for ground (suspension) and underground cable laying, including. If the route is long, and you want to be able to pull the cable “in case of emergency” without replacing the corrugations, develop the route taking these rules into account.
Installation of wiring in the corrugation
When installing wiring in a house or apartment, pieces of corrugation are fixed between junction boxes, from them – to switches / sockets, to lighting fixtures. Here the sections are usually small, straight, with a maximum of one or two turns. So there are no problems with tightening the cable.
If several conductors are needed to be tightened into the corrugation for the cable, they are folded, fastened along the entire length with adhesive tape or electrical tape in increments of 30-50 cm (depending on stiffness). Rigid insulation is stripped from one edge by 10-15 cm, the wires are twisted into a common bundle, a loop is formed from it (secure the loop with tape or electrical tape, too). If the tourniquet is too thick, you can form the loops separately, just stretch the twine through everything. A cable is tied to this loop, and then they begin to pull it from the opposite side, pulling the sheath over the cables. At the same time, it is necessary to pull without jerking, smoothly – so as not to damage the cable or cable.
When installing, be careful not to slip the broach. To be sure, you can secure the cable with a piece of tape. There are two installation approaches:
- First fix the corrugation, then tighten the cable or wires into the finished piece.
- First stretch the cable, then mount it.
The first method is good when installing internal wiring, where the distances are small – from the box to the box, from the box to the outlet, etc. The second method is more suitable for installation of long sections.
Features of open laying on the street
When laying wiring on the street, it is usually suspended on a cable. For outdoor use, metal stainless steel is suitable, and better – metal-polymer corrugation for cable, as well as plastic polyamide (black or blue). All these materials are UV resistant and remain flexible at sub-zero temperatures.
During installation, the cable stretched into the corrugation is suspended on a cable. The cheapest mount is ordinary plastic ties. There are also special hangers.