Distribution box - a hollow structure mounted on a wall and containing inside the connection wires. Differs from the shield simplicity and lack of sophisticated equipment.
. Design of the distribution box.
. The distribution box is of various sizes and shapes of plastic boxes with tapered cable glands. The design is protected by a removable lid, fastened with four or more screws. There are other versions, where the fastener is missing. And the lid is held by the forces of elasticity.
Cable entry by cutting the required number of segments is brought to the required size in diameter. Plastic is taken for the manufacture of an elastic junction box, so that the insulation( cambric) is compressed tightly and prevents moisture from getting inside. Seizures do not bring much benefit in apartments, other material is allowed.
In panel houses, junction boxes often became part of concrete or made of steel. For practical reasons, this is convenient. Pry such a box out of the wall is extremely difficult. Partitions assembled from gypsum blocks, brick and concrete, were supplied with junction boxes( and under the hood) of durable elastic polyethylene.
Switchboard
Modern designs are often overhead, it is not prohibited for a builder to build a building into the wall. In this case, as a rule, deteriorating operational properties. For example, a smaller thickness in the cold season will cause condensate to fall on the electrics. However, the process can not be called intensive.
Varieties of distribution boxes
Commute requires electricity, television, telephone, computer networks. For these networks, industry produces a special type of junction box. The power cable for laying into the ground is not too different from the information cable, which cannot be said about the wires. It is worth knowing how it is allowed and not allowed to use junction boxes.
Rarely think about it, the simplest question is - how does a cable differ from a wire? You should not run and flip through GOST, official documents do not give an answer. The difference in structure. The cable is characterized by tangible protection, for example, armor. The wire has no powerful structures.
Now it is clear why the junction box for power networks is not suitable for laying information. And replacement is impossible. For the time being, the violations are getting away with hands, then the hour comes. X.
If we talk about the laying of information networks, the provisions are affected in the EIR.This set of rules in some places is not approved at the legislative level, although builders and installers are trying to fulfill the requirements. Regarding the aforementioned case, the rule is given:
. Joint installation of networks with voltage up to and above 42 V is not allowed. It is mentioned that joint laying is permitted for lighting purposes only or in different compartments of the same tray, if the fire resistance of the partition does not exceed 0.25 hours. The flame does not spread to the adjacent compartment earlier than 15 minutes.
Why it is impossible to lay out jointly information and power networks
It seems that the law does not prohibit to start simultaneously a number of different networks, information and power, directly into a common junction box, but the opinion is wrong. The Electrical Installation Code states that the equipment case with power above 42 V AC( between phases or relative to the ground - indifferently) must be grounded. Now imagine a case when the wires in violation of the laid paved. Suppose there was a breakdown of the insulation, on the 42V wire it failed 220. If the equipment does not fail immediately, there is a chance that the potential will be on the case. A touched person will immediately receive shock.
Skeptics will answer that the screen of the cable of the television antenna is necessarily grounded in the area of the distribution panel. For example, on the site in front of the apartment. But the credibility of this statement is controversial, there is no certainty that there is a reliable ground. The screen can quite connect with the TV case. Accordingly, in the described situation there is a chance of a fatal accident. Speaking in detail, 42 VAC is another electrical safety class, or a safe supply voltage.
Cabling
In addition to the nuances explicitly stated in the standards, there are constructive differences between networks. For example, the power wires do not detect the screen. If such to lay in the soil, when wet weather forms a parasitic capacitive coupling, the current will flow into the ground. Here the owners will not need to explain, the accounts of management companies will say themselves. Armor cables protects them from mechanical damage, encroachment of flora and fauna. Wires do not need such precautions. Information cables are enclosed in a shield to protect against interference and prevent the radiation signal in the air.
Examples are taken from lively discussions and forums, which directly indicates a lack of information in terms of wiring rules. The authors have seen the telephone and power wires resting in a tray next to each other. Conclusions about the above:
- Do not confuse information networks with low-voltage power( up to 42 V AC or 110 V DC).The EMP explicitly states that for the first the screen, and hence the case, is invariably grounded, for the second the measure is sometimes lowered. This document is applicable only to power circuits and circuits with expressly stated purpose. A hint of an exception is made when joint laying of control and power circuits of a geographically combined equipment is allowed. A standing conveyor demonstrates an integrated grounding bus; during an insulation breakdown, the fuses will operate. The production cycle will stop, but people will not suffer - justifying the main task of safety rules.
- In Russian practice, there are no standards that directly regulate the rules of installation. Standards of the industry stand out, it is worth studying for a proper understanding of the subject matter.
Connection of wires
Rules for the installation of telephone lines
Regulations are considered to be "Guidelines for the construction of linear structures of local communication networks" and "Instruction for the design of linear-cable communication structures."When laying the underground route, there are indents from engineering structures. For cable ducts of any kind, the distance is 25 cm horizontally and 10 cm vertically. Separate power cables that are not protected by concrete structures should be avoided more strictly: 60 cm horizontally, 50 cm vertically. Other requirements have been developed, part of which takes into account the parameter - the specific resistance of the soil in the laying area.
The builder should not even have thoughts to pave two different types of engineering communications together. When arranging the collectors( a place for collecting lines for various purposes, including heating lines), it is indicated where the lines are located, separated from each other by the prescribed distance. Each cable lies on a support, and the passages through the walls are made with pipes and do not touch.
Telephone line
Rules for the construction of computer networks
The concept of a personal computer was invented in the USSR, but was developed in the west. Standards come from overseas along with features. In the west, it is customary to pay honestly for everything. The ISO has spent time, conducted research and formulated requirements in the form of ISO / IEC 14763-2 and other documents, wanting to get money for their work. The cost of the document varies around 10,000 rubles( after the situation with Ukraine).
The European equivalent of the world is considered EN 50174-2.It is a fabulous amount for ordinary citizens and is not available for download or open study. In RuNet, under a certain pretext, some information is laid out. It becomes clear that the laying of power and information cables inside the premises is not allowed. Between the lines it is supposed to leave a gap, depending on the magnitude of the current of the cable with voltage of 220 V, on a number of other conditions. The concepts of the tray, PUE appear.
From what has been said, the conclusion is being asked that similar studies have not been carried out by domestic laboratories, and the legality of publishing information from paid documents remains incomprehensible.
Using junction boxes
A common junction box should not be used to install disparate lines. Power and communication cables are required to lie separately. We assume that in the USSR there was no question, telephone communications went along the plinth, not covered by anything. Computer networks were not, if you do not take into account the military facilities. There and at the enterprises similar communications lay directly under a sexual covering.
It is not recommended to use junction boxes for other purposes. For example, often people do not see the difference between dielectrics. Insulation of information and power lines is carried out with different polymers, with specific requirements:
- At high frequencies, the tangent of dielectric loss dominates.
- Increased voltage requires high electrical and mechanical strength.
The listed conditions are not related. And only developers know what properties are laid in the product. As a result of the use of low-quality equipment, anything is possible. For example, the purchased splitter for a TV antenna turned out to be a box with ordinary wire switching. The wave properties of the signal and radiation were not taken into account. As a result, the quality of viewing programs has greatly decreased.
