Is There Any Relationship Between The Thickness of The Sheath Layer And Wire Insulation Layer?

In the eyes of senior electricians, if the thickness of the sheath layer of the sheathed wire is lower than the requirements of the national standard, it is considered unqualified, but if the thickness of the outermost layer of the sheathed wire exceeds the requirements of the national standard, it is also unqualified. Just like the shielded cable RVVP3 core 1.5 square sheathed wire, the average thickness of the sheath is 0.8mm. If this model refers to the national standard, the thickness should be 1.1mm. The reasons for disqualification are as follows:

1. Reduce the service life

After the sheathed cable is laid, the sheathed cable will often heat up if it is energized for a long time. The allowable operating temperature of the conductor is 70°C. The long-term use temperature of PVC sheathed wire should not exceed 65℃.

If the weather is hot, the operating temperature will naturally increase, and these temperatures will be distributed through the outer sheath. If the thickness of the sheath of the wire is relatively thick, then its heat energy is difficult to dissipate, which will affect the service life of the cable. Due to the action of heat, the insulation layer of the cable undergoes physical and chemical changes, and the sheathed wire loses its original excellent performance, resulting in a significant decline in insulation performance, and even short circuit, which affects the normal operation of the unit.

2. Defects in the material properties of the sheathed wire

Material properties are not reflected in thickness. According to the national standard requirements, if an index of the sheathed wire does not meet the standard, flame retardant PVC material, then its oxygen index is below 30.

3. There is a problem with the sheath wire structure

If the conductor cost, insulation and braid density are controlled according to the national standard, and suitable fillers are selected to make them round, how can the outer sheath of the cable be squeezed so thick? Control the conductor cost, insulation and braid according to the national standard density, choose the right filler to make it round, so how can the outer sheath of the cable be squeezed so thick?

4. Increase the difficulty of cable laying

At present, the laying of cables is mainly based on bridges or pipelines. Many companies are now implementing strict cable requirements and small outer diameters. During the laying process, the sheathed wire can leave a gap to dissipate heat energy to ensure that the outer sheath of the cable is not damaged. Otherwise, it will be handed over to the construction unit, and the laying of cables will bring certain difficulties.

All in all, the sheath thickness of the cable needs to be controlled in accordance with the national standard, which is what cable manufacturers should do. It not only saves sheathing line resources, reduces material consumption, and increases profits for enterprises, but also ensures the quality of cables and creates high-quality and low-cost protection. set of cables.