Cable lines are distinguished, among others, by lower failure rates, but if technical problems arise, repair is more troublesome. So you need to take care of safety when laying, for example using cable scissors. It is also necessary to plan a cable line route and a particularly accurate cable protection in places where the risk of damage is extremely high.
Basic rules for determining cable lines routes
Although cable lines are distinguished by high life, there must be good access to the wires. The route should run in such a way as to minimize the number of intersections, close -ups and go through various types of obstacles (e.g. walls, ceilings). When the cable is in the ground, it should run along the roads and pavements. They can also be carried out along water reservoirs, provided that the place is not exposed to washing through water. In special cases, cables can be run through zones and rooms at risk of fire or explosion, but only if they are necessary to power the devices located there.
Battery scissors are useful for cutting the cables, because the wires should have coatings, armor and covers that protect against the harmful effects of the environment. If there is a threat of stretching stress, armored cables with wires work. It also happens that the lines are laid in places exposed to soil movement and the appearance of wandering currents. It is then necessary to protect them using plastic covers. Cable lines are so universal that it is even possible to run them under water. However, they must have anti -corrosion cover -pressed plastic cover. Particular care should also be taken when laying cables in cable tunnels, channels, covers and rooms - should have special fire resistance. The use of ordinary cables is permissible if fire protection will be used.
Cable protection methods against damage
Despite the thoughtful lead of the cable line, it is impossible to completely avoid factors that can lead to wire damage. In some places, it is necessary to use special security.
Of course, mechanical damage is of course the most common. When creating a line, a hydraulic winch is needed, ensuring the right strength and speed of laying. Wherever mechanical stress appears, the cables should be laid in covers. They are used especially on bridges, viaducts, under roads and tracks and at the height at which they are available to bystanders. Some cables can be laid without shields, if they have rated voltage not more than 30 kV and are located under roads with a surface that can be dismantled or under local roads with non -detectable surface (if there is a free surrounding cover in parallel). The location of the cable from the cover is very important - you need to protect it from bending.
Corrosion protecting covers, erring currents and ultraviolet radiation are also available.
Cable ends and connection
If the rated voltage of the cable does not exceed 1 kV, the most important thing is to protect it against moisture penetration into the interior. The end of cables with higher rated voltage require cable heads. This can be abandoned, provided that the voltage does not exceed 6 kV, and the working veins will be protected against moisture.
Cable muffs are used to connect cables. Both muffs and heads are selected because of the cable type, rated voltage, cross -section, number of veins, short -circuit conditions and determined load. MUF cannot be used everywhere: explosion -threatened places, rooms, tunnels as well as cable windows and windows are excluded. If this cannot be avoided, the muff cannot be made of cast iron.
Connecting places are weak points of the cable line, so they must be well protected: they should have their own insulation and be tightly attached to the cable coating. Common insulation is permissible only if the rated voltage does not exceed 1 kV, and the interior of the muff is made of material ensuring good insulation and sealing.
Anti -tire protection
It is also necessary to ensure anti -tire protection, so you should ground the metal parts of the heads. If the connection with grounding is not possible, you must use other protection against paralysis. When the insulation material is used, the metal coatings, return veins and cable armor should be combined with grounding. It is worth remembering that the short -circuit load capacity of metal elements of cable coatings, return veins and armor cannot be lower than the short circuit capacity of combined coatings, return veins and armor.
One of the advantages of cable lines is safety, but for this to be so, you need to follow a number of standards. That is why the cable line must be properly designed, and you must also take into account protection against factors that can cause damage.
