The cable is usually a rope-like cable that is stranded by several or several groups of wires (at least two in each group). Each group of wires is insulated from each other and often twisted around a center. The bread has a highly insulating covering. Many are erected in the air or installed underground or underwater for telecommunication or power transmission. Cables can be divided into power cables, communication cables and control cables according to their uses.
There are many types of wires and cables, and the quality of various cables in the market is uneven, and the quality of them directly affects the quality of the project and the safety of consumers' lives and property.
Then, are there any safety requirements when the cable is used? What are its protection measures? How to store it?
1. Safety requirements
1. When the cables cross each other, the high-voltage cable should be under the low-voltage cable. If one of the cables is protected by a pipe within 1m before and after the intersection or separated by a partition, the allowable distance is 0.25m.
2. When the cable is close to or crossed with the heat pipe, if there are thermal insulation measures, the parallel and cross distances are 0.5m and 0.25m respectively.
3. When the cable crosses the railway or road, it should be protected by a pipe, and the protection pipe should extend beyond 2m from the track or road surface.
4. The distance between the cable and the foundation of the building should be able to ensure that the cable is buried outside the building's bulk water; when the cable is introduced into the building, it should be protected by a pipe, and the protection pipe should also extend beyond the building's bulk water.
5. The distance between the cable directly buried underground and the grounding of the general grounding device should be 0.25~0.5m; the buried depth of the cable directly buried underground should generally not be less than 0.7m, and should be buried under the permafrost layer .
Two, protection measures
With the rapid development of power cable buried laying projects, higher requirements for cable protection are put forward. Made by warm curing process.
This is an electrical insulating tube commonly used to protect wires and cables. It is widely used because of its good insulation performance, high chemical stability, no rust, no aging, and adaptability to harsh environments.
Protecting cables with cable protection sleeves can achieve the following advantages:
1. Good corrosion resistance, long service life, can be used in humid saline-alkali areas.
2. Flame retardant, good heat resistance, can be used for a long time at 130 degrees without deformation, and will not burn in case of fire.
3. High strength and rigidity. It can be used for direct burial under the roadway without adding a concrete protective layer, which can speed up the construction progress of the cable project.
4. The cable protection sleeve has certain flexibility whether it is a pipe material or a pipe fitting, and can resist the damage caused by the external heavy pressure and foundation settlement.
5. Has good anti-interference performance of external signals.
6. The inner wall is smooth and does not scratch the cable. The design adopts socket-type connection, which is convenient for installation and connection. The rubber sealing ring seal at the joint not only adapts to thermal expansion and cold contraction, but also prevents mud and sand from entering.
Three, storage method
1. Under the eaves. Standard LAN cables can be used only if the cable is not exposed to direct sunlight or high temperatures, and conduit is recommended.
2. On the outer wall. Avoid direct sunlight on the wall and man-made damage.
3. In pipes (plastic or metal). If in pipes, pay attention to the damage of plastic pipes and the heat conduction of metal pipes.
4. Suspended application/overhead cable. Consider the sag and stress of the cable, which bundling method you plan to use, and whether the cable is exposed to direct sunlight.
5. Directly laying in the underground cable trench, this environment has a small control range. The installation of the cable trench should be checked regularly for dryness or dampness.
6. Underground pipes. In order to facilitate future upgrades, cable replacement and isolation from surface pressure and surrounding environment, auxiliary piping is a better method. But don't expect the pipes to stay dry forever, which will affect the choice of cable type.
4. Supplementary Matters
1. If you want the cable to be stored for a long time, you must avoid contact with acid, alkali and mineral oil.
2. It is strictly forbidden to exist with harmful cables (tinned copper wire or bare copper wire) in the warehouse where wires and cables are stored.
3. Cable storage should be regular, according to specifications and appearance time, in order to facilitate the safe storage of cables. The cables should be used within one and a half years from the time of leaving the factory. If they cannot be completed, they should not be stored for more than two years.
4. Because the cable is stored in the process, the different degrees of extrusion due to the long time and the different degrees of softness and hardness of the protective cover will have a certain impact on the cable, so it should be rolled regularly during the storage process (summer Once every 3 months, other seasons can be postponed as appropriate). During the rolling process, in order to avoid getting wet, the side of the tray should be rolled down and turned up. After rolling, it is necessary to check whether the wires are in good condition.
5. The transportation of electric wires is also the key to the storage and protection of electric wires. During transportation, it is strictly forbidden to throw the cable tray from a high place, which may cause the insulation and sheath to crack.
6. It is strictly forbidden to lay the cables flat during storage, otherwise the insulation layer or protective sheath will be worn to a certain extent. It is conceivable that the damage to the bare stranded wire will be more serious. And if the cables are laid flat and the arrangement is disordered, it will inevitably affect the quality of the wires to a certain extent.