In modern society, the electrical systems are becoming more and more complex in building construction. The usage of wires and electric cables are increasing. Wires, cable accessories, and pipes are criss-crossed and scattered in buildings, which brings convenience to our lives. However, on the other hand, the extensive use of wire and cable, some unsafe factors and the weak awareness of people's safe use about electricity have also led to an increasing incidence of wire and cable fire accidents. In order to enhance people's safety awareness, protect life safety and property safety, and improve the safety and reliability of electrical systems, let us learn more about the safety of cable use.
1. When the cable lines cross each other, the high voltage cable should be below the low voltage cable. If one of the electrical powers is protected by a pipe or separated by a partition within 1 m from the intersection, the minimum allowable distance is 0.25 m.
2. When the power line is close to or intersects with the heat pipe, the minimum distance of parallel is 0.5m and the minimum distance of intersection is 0.25m if there is insulation.
3. When the cable crosses the railway or the road, it should be protected by a pipe. The protection pipe should be 2m away from the track or road surface.
4. The distance between the cable and the foundation of the building should ensure that the cable is buried outside the building. When the power cable is introduced into the building, it should be protected by a pipe. The protective pipe shall also be outside the scattered water of the building.
5. The distance between the cable buried directly in the ground and the grounding of the general grounding device should be 0.25~0.5m. The buried depth of the cable buried directly in the ground should not be less than 0.7m and should be buried under the frozen soil.
With the rapid development of power cable buried laying projects, higher requirements are placed on cable protection. The cable protection sleeve is made of polyethylene PE and high quality steel pipe through sandblasting pretreatment, dip coating or coating, heating and solidification process. It is the most commonly used electrical insulation tube for protecting wires and cables. The cable protection sleeve is widely used because of its good insulation performance, high chemical stability, no rust, no aging, and adaptability to harsh environments.
Protecting the power cable with a cable protection sleeve can achieve the following advantages.
1. Good corrosion resistance and long service life. It can be used in the wet and dry saline zone.
2. Good flame retardant and heat resistance. It can be used for a long time at 130 °C without deformation, which does not burn in case of fire.
3. High strength and rigidity. It can be used directly under the carriageway without the need to add a concrete protective layer.
4. The cable protection sleeve has certain flexibility whether it is pipe or pipe fitting, which can resist the damage caused by external heavy pressure and foundation settlement.
5. It has good resistance to external signal interference.
6. The inner wall is smooth and does not scratch the cable. The design adopts a socket type connection for easy installation and connection. The rubber sealing ring seal at the joint not only adapts to thermal expansion and contraction, but also prevents mud sand from entering.
If the power cable is stored for a long period of time, the following considerations should be made depending on where the cable is placed.
1. Under the eaves. As long as the cable is not directly exposed to sunlight or high temperatures, standard LAN cable can be used. Pipes are recommended.
2. The outer wall. Direct sunlight on the wall and human damage should be avoided.
3. In the pipeline. For example, in the pipeline, attention should be paid to the damage of the plastic pipe and the heat conduction of the metal pipe.
4. In the underground cable trench. Electric cable trench installation should be checked regularly for dryness or humidity.
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