Categories: Electrician Secrets, Electric installation work
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Errors in wiring in corrugation

 

Modern electricians lay wiring in the corrugation on the street, indoors, on the surface and inside the walls. Despite all the advantages of this installation method, there are a number of features of its use. The fact is that there are three varieties of corrugations and each of them is intended for use for certain purposes. In this article we will look at typical errors when laying cables and wires in the corrugation.

Errors in wiring in corrugation

Types of corrugation

Oddly enough, it sounds, but the corrugation is chosen by color. There are three main materials for the production of corrugated pipes, so as not to make mistakes in the future, remember:

  • White or gray - polyvinyl chloride (PVC);

  • Black or orange - low pressure polyethylene (HDPE);

  • Blue - polypropylene (PPR).


What is the difference between corrugations?

PVC corrugations are used indoors, and they crack due to ultraviolet radiation. But this material does not support combustion. The mechanical strength is lower than that of analogues. By the way, it is the cheapest, lightest and most flexible.

HDPE corrugations are durable, so they are used for laying cables in the ground. Their disadvantage is that they are combustible. Also, black corrugation is laid on the street because it is resistant to ultraviolet radiation.

PPR-corrugation is self-extinguishing, it, like PVC, burns only as long as there is a source of flame, but goes out when it disappears. Other characteristics are like HDPE.

Products of the last two types are much more expensive than PVC.


Benefits of using

The technology of working with a corrugated pipe is quite simple. Inside the pipe there is a wire for pulling the wire, it is called a probe. The wire or cable core is tied to the probe and the probe is pulled from the other end of the corrugation by tightening the conductor.

Corrugated pipe for electrical wiring

Corrugated pipes are mounted either in a concrete screed on the floor, or behind false walls, panels and on the main ceiling by covering with suspended and tension structures, and wiring along combustible coatings such as wood is also laid in the corrugation. As fasteners, clips or dowels are used.

Corrugation Mount

Thus, installers have the opportunity to reduce the amount of gating, and to fasten the wiring on the walls and ceilings using an automatic tool to drive dowels, which speeds up the work and when working there is almost no debris and dust.

Automatic tool for driving dowels

disadvantages

Corrugations have their drawbacks, because of which you can make a mistake. For example, we mentioned that when using PVC corrugation on the street you will not get good results - it will crack from frost and ultraviolet radiation, in simple words from sunlight. Underground it is also better not to use it, the strength is much lower than that of the HDPE pipe. This means that the cable protection will be insufficient and the PVC corrugation together with the cable may be damaged as a result of the movement of soils and sharp objects that are in it.

In this case, the use of HDPE corrugations in the room can lead to the spread of fire in the event of a fire.

It is worth noting that there is often information that the cable laid in the corrugation can be easily replaced. This is not entirely true, since cables with monolithic conductors are quite rigid, and it is not always possible to remove it from the pipe.

Rodents - are a danger to the insulation of conductors and to corrugated pipes. This means that if you are wiring in places where rats or mice are often wound up, it is better to use a metal hose. Such premises include sheds, cellars and other utility structures.



Top 4 questions about corrugation for cables or how not to make a mistake when choosing

We will consider several situations with answers on how to route wiring safely and without errors.They were selected as a result of a long analysis of online communities and personal experience, this is what people often ask.

The first situation: “I have an air inlet into the house. From the support there is a SIP cable, comes to a pipe rack installed on the facade. How to make the transition to copper and get inside? Can I use the VVG cable (sometimes ask for PVA or others)? If not, is it possible to lay it on the facade in gray PVC corrugation? ”

The answer to the last two sentences is a categorical “NO”. Cables with PVC insulation, type VVG and its modifications are not used for outdoor installation on the street. Rather, you can use it without protection only in temporary postings. He will serve in this case from 3 to 10 years. The reason for this is all the same ultraviolet and frost, due to which the insulation will crack, as a result, short-circuit will occur.

If you pack the cable in a PVC corrugation, and this solution is the most common because of its cheapness, this will slightly improve the situation, but not for long. It will also crack in the cold, become brittle from ultraviolet exposure, and from the heat will begin to soften and flow (although the latter is not so significant). Although if this part of the facade is in the shade and not on the sunny side, as well as in your region, frosts are rarely below -15, then this is quite an acceptable option.

Using corrugation outdoors

Therefore, the option remains to use HDPE or PPR. Black PND is usually recommended, according to the manufacturers, it is specially designed to reflect UV rays and resistance to their effects. It is also possible to use a metal hose for the input cable, but this option will be the most expensive, and you also need to remember about grounding the sleeve from both ends.

Situation two: “It is necessary to conduct electricity in the garage (barn, gazebo) and connect the lamps on the street. I will lay the wiring on the fence, and then on the posts with a ball screw or PVA wire. ”

In this case, you should also not use PVC corrugation, especially with such brands of wires. Suitable black PND-corrugation. Or galvanized metal, otherwise it will simply rot.

Rotten pipe

And in the photo below you can see the state of the white and black corrugations laid on the street through time.

Situation three: “It is necessary to conduct electricity in the bathhouse, I am considering the option of laying in a trench, which cable and type of pipe are best used. Is it possible to do without laying in the pipe? ” .

For underground laying without pipes, armored cables with copper conductors of the VBBSHV type, or with aluminum AVBBSHV, are suitable. If you cannot find such brands of cables, it is better to choose a cable of type VVG-ng-ls and lay it in a corrugated PND pipe. Using PVC corrugations for underground installation will be a mistake for two reasons:

1. It does not withstand such mechanical stresses as HDPE.

2. When laying at a shallow depth, do not forget about the effect of frost on the product.

If you lay the cable under the platform for the car or under the road - you can use either a two-layer PND pipe, or in this section, lay the cable in the corrugation and metal pipe, or just a metal pipe, or corrugation in a PVC sewer pipe.

Important:

When laying the cable through the wall, the minimum you need is to go through the hole in the thick-walled heavy corrugation. To eliminate the error - you can use a metal or thick plastic pipe to enter the building, even underground through the foundation, even above the ground into the wall. This will save the cable from abrasion and mechanical pressure of the walls in case of precipitation, which is especially important for those who are building a new house from cinder block, brick and other types of blocks.

So it looks in a schematic illustration:

Cable routing through the wall

And so in practice:

Cable routing through the wall

The fourth situation: “It is necessary to conduct wiring to spotlights, which will be installed in a suspended ceiling made of drywall (or suspended ceiling), which wire is better to use and how to mount it? Is it possible to do without gating? ”

In this case, the use of PVC corrugation will not be a mistake.Laying in dry rooms is its true purpose. In this case, the installation is carried out by attaching to clips or clamps, or fixing them with screws, or dowels from the gun.

Strobing will be needed only if the switches are connected - to lower the cable in the wall. At the same time, it can be laid in the strobe both without corrugated pipes and in them. The same method of wiring can be used in other structures made of gypsum plasterboard - false walls or panels and other decorative structures.

Recall that when installing wiring in the room it will be a big mistake to use HDPE pipes because of their combustibility. And in the case of laying cables in such a sheath through the walls - in case of fire, the fire will spread to other rooms. Moreover, when burning, PND pipes begin to flow, like fire rain, especially with group laying.

IMPORTANT:

HDPE corrugations are not recommended for use in the room due to the fact that they burn well.


Why can corrugation catch fire?

Finally, we consider why there may be a fire in the wiring laid in corrugated pipes, and why it is necessary to take into account the issue of the spread of combustion by one or another material. The popular misconception that wiring in corrugations is needed in order to ensure fireproof wiring. It is also widely believed that the source of ignition are sockets, junction boxes, lamps and other electrical points.

In addition to the fire of the wiring at the connections with poor contact, we must not forget about the circuit between the wires somewhere in the middle of the cable. This may be due to environmental influences, manufacturing defects or elemental aging. Under the influence of the environment is meant mechanical shock and damage (from which the corrugation protects to a certain extent), as well as the harm caused by rodents.

Also, the insulation of the cores is damaged under the influence of overcurrents of short circuit and overloads. This leads to the melting of the shells and the heating of the veins themselves. And as a result of sparking, arcs, and heating of the conductors, ignition of the surfaces surrounding them can occur.

In the case of laying in the corrugation - its fire. Therefore, the use of PVC corrugation in the room is due to the fact that in the event of a flash somewhere inside the pipe and even short-term ignition, the fire source will self-destruct. For the same reason, it is recommended to pay attention to cable products, the insulation of which does not spread combustion, usually the letters "ng" are added at the end of their marking. For example, beloved by modern electricians VVG-ng-ls.

Corrugated pipe on a wooden surface

Conclusion: how to carry out wiring and not make a mistake

When purchasing goods for independent work or when controlling wage workers, do not let yourself be deceived. To do this, remember the three rules for all occasions:

1. For laying behind drywall or on combustible, for example, wooden, surfaces in the room - use gray PVC corrugation.

2. For installation on the street, on the facade of buildings, supports, fences, and so on - use black HDPE corrugation.

3. An orange HDPE pipe is suitable for underground installation. In case of increased loads - multilayer.

See also at i.electricianexp.com:

  • What cable can be used outdoors and how to lay it
  • Laying the cable through the air in the country
  • Corrugated pipe for electrical wiring
  • Open wiring - popular wiring methods
  • Ways of laying wires and cables for various building structures

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    Comments:

    # 1 wrote: Valery | [quote]

     
     

    Cable laying underground in metal pipes is prohibited.
    The use on the street of a metal corrugation (metal hose) is paid.
    HDPE is unstable to ultraviolet radiation material. According to the manufacturer's specifications, they are classified as light-resistant types of corrugations with a special one with a polymer coating and a UF mark. In advertising about this, it is quite possible to remain silent by declaring that it is all lightfast.

     
    Comments:

    # 2 wrote: Igor | [quote]

     
     

    The air there inside the HDPE pipe is exactly the volume of the pipe minus the volume of the cable. The air is closed inside the HDPE pipe as well as when laying in a metal pipe. The difference is only in the thermal conductivity of plastic and metal, but this is secondary. Since the air in the pipe is small and calorific only this air volume is limited. Judging by the thermograms of the thermal imagers, the air is quite actively heated and in a closed volume it maintains for some time the temperature to which it is heated is not particularly affected by the outer shell. The temperature is well maintained inside. As a result, we get more heating of the cable in any pipe compared to open and practically infinite volumes of air with an open gasket. This must be taken into account when choosing a pipe for the cable.

     
    Comments:

    # 3 wrote: Merkulova Tatyana | [quote]

     
     

    Among the current variety of manufacturers and models, it is really hard to find good and high-quality material.