Precautions for laying and installing pre branched cables
Pre branch cable is a type of cable that is prefabricated by the factory during the production of the main cable according to the customer's design drawings. It is a new technological product in recent years. Compared with the original technology, it has excellent seismic resistance, air tightness, and water resistance.
Pre branch cables are cables made by factories to prefabricate branch lines based on customer design drawings during the production of main cables. It is a new technology product in recent years, and the branch line factory pre manufactures it on the main cable. The size of the branch line section and the length of the branch line are determined according to design requirements, which greatly shortens the construction period, greatly reduces material and construction costs, and ensures the reliability of power distribution.
Pre branch cables are cables produced directly from the main and branch lines of cable factories after on-site measurement. No need to bring it to the site for branch joints, greatly saving project time and costs.
When a relay cable requires branching, branch cables can be used, especially in high-rise buildings. If ordinary cables are used without branch cables, a cable from the bottom to the top of the building needs to be decorated as the main line. In order to connect each floor of the distribution box, branch circuits are required. During on-site construction, it is necessary to connect branches on the main line. Laying branch cables on site is not only time-consuming and labor-intensive, but also has lower joint quality. Branch cables are prepared in advance in the factory, reducing the workload on the construction site and ensuring the quality of joints.
(1) Try to use front suspension when laying. When the construction site is limited or there are special requirements, reverse hoisting can also be used. Regardless of the setting, it is not allowed to release the branch line in advance in the process to prevent scratches when the branch body passes through the hole, and to avoid excessive mechanical external forces.
(2) When hoisting, it is necessary to use ropes with a cable weight of more than 4 times. After laying, the fixing fixtures should be installed from top to bottom first.
(3) The bending radius of the cable during laying and installation shall not be less than 25D.
(4) When fixing single core prefabricated branch cables, the use of metal clamps is prohibited.
(5) When connecting electrical measuring and measuring instruments to main and branch lines, it is necessary to use metal wire clamps and correctly select the metal type of the wire clamp.
Pre branch cables are mainly used for distribution relays in high-rise buildings. The main cable conductor has no joints (the joints are processed and enclosed at the branch points when leaving the factory), and the distribution of branch cables is similar to that of bus ducts. However, the cable has good seismic, sealing, and waterproof performance, occupies a small area, and is easy to install. The disadvantage is that quality faults need to be repaired on site, and the conditions are not interchangeable for specific engineering and cable processing. For example, a building has 24 distribution floors, each with a branch. The main line is divided into 3 lines (each line has 8 distribution layers and a current of 315A). Each layer has one cable with a current of 40A. 2. Specification of relay cable YJV-4 * 185+1 * 95. Specification of branch cable YJV-5 * 16. Separation length of 2m; 3. The standard floor height is 3m, and the length from the distribution room to the first floor is 80m; 4. (feeder cable 3 * 80m), finished pre branched cable 3 * 25m, support spacing of 3m, and 3 cable transition boxes.