In order to ensure the accurate processing and manufacturing of prefabricated branch cables, and the product quality meets the requirements, the following items must be accepted for the cables.
1. Check the certificate of conformity, relevant technical documents, and product certification marks produced according to national standards.
2. Check whether the model, specification, length, and voltage level of the trunk and branch cables meet the design requirements.
The appearance of the cable is intact, without flattening or twisting, and the sheath is free of aging and cracks. The cable head is tight.
4. The outer protective layer of heat resistant and flame retardant cables shall have obvious identification and manufacturer's logo.
5. Perform insulation shake test on the cable, using an insulation resistance meter with a range of 1000V and a resistance value of ≥ 10 megohms.
Precautions for installation and laying of prefabricated branch cables
When prefabricated branch cables leave the factory, the branch cables are tied to the main cable. After the main cable is installed and fixed, the branch cables can be untied.
Before installation, the top of the cable shall be treated with a waterproof cap, and then compressed and strengthened with a heat shrinkable tube.
During installation, attention should be paid to fixing the branch cable to avoid shaking of the branch cable to ensure good contact between the internal crimping parts of the branch connector.
4. Ice level buried laying is the same as ordinary cables. It is worth noting that branch joints are not suitable for pipe laying, so it is important to avoid laying in environments prone to mechanical external forces.
"The vertical laying of prefabricated branch cables is different from the laying of ordinary cables, and requires supporting installation accessories, including hangers (or cross arms), cable supports, cable fixing clamps, and hanging head devices for fixing the upper end.".
To prevent eddy current effects, it is strictly prohibited to use iron clamps for single core cables, and use saddle plastic clamps to fix them; Single core cables cannot be threaded through a single steel pipe. When threading, four cables A, B, c, and N must be threaded through a single steel pipe.
Before laying, check the cable channel to confirm whether the branch cable can safely pass through the hole, and formulate detailed preventive measures to prevent the branch part from being damaged when passing through the hole during the lifting process.
During the lifting process, do not apply tension to the branch cable. Use a lifting rope with a strength of more than 4 times the weight of the cable. After the cable is lifted, immediately fix the lifting head on the top of the cable to the hanger, and immediately fix the main cable with fixed clamps at intervals of 1.5>2m. Distribute the weight of the prefabricated branch cable evenly on the bracket in the shortest possible time to prevent local stress on the cable and damage from falling.
After installation, the cable openings shall be sealed with fireproof blocking materials, and cable signboards shall be hung at the ends and branches of prefabricated branch cables.
epilogue
The emergence of prefabricated branch cables has changed the long history of producing cable heads at construction sites, and is a major breakthrough in wires and cables for low-voltage distribution systems. It has excellent power supply reliability, good seismic resistance, air tightness, waterproofing, construction convenience, low environmental requirements, maintenance free, and other characteristics. The application of prefabricated branch cables in China has been rapidly promoted. With the acceleration of various infrastructure construction and real estate development in China, the market has continuously increased the requirements for the application types of prefabricated branch cables, and the performance requirements have continuously improved. For example, from the initial ordinary cable to the requirements for flame retardance, fire resistance, halogen-free low smoke flame retardant, from small cross-section to large cross-section, from the initial single core to multi-core, and so on, The application prospect of prefabricated branch cables is very broad. After all, prefabricated branch cables are a new member of the cable family. In order to adapt to the further development of prefabricated branch cables, understanding and mastering prefabricated branch cables and precautions for their use is crucial for their promotion and application.