How Does Cable Wrapping Affect The Fire Resistance Of Cables?

The insulation materials for fire-resistant cables are generally PVC, PE, XLPE, etc. In the high-temperature combustion state of 750 ℃, the insulation layer of the cable basically no longer exists. The purpose of the insulation layer is to ensure the electrical performance of the cable under normal conditions and to protect the fire-resistant layer. It does not determine the fire-resistant characteristics of the cable, but the influence of the insulation layer state on the fire-resistant layer during high-temperature combustion should be considered.
If the cable wrapping layer is made of combustible non-woven fabric or PVC tape, it will be basically burned out together with the insulation during combustion, which can provide enough space for the stress deformation caused by temperature fluctuations to diffuse and release outward, resulting in less compression damage to the refractory layer and therefore less impact on the refractory performance. If the cable wrapping layer is coated with adhesive glass ribbon or mica tape, due to the fire-resistant properties of the wrapping layer, the insulation material is not directly burned by the flame during combustion, but rather melted by heat.
Due to the fastening effect of the wrapping layer, the stress deformation caused by the melting of the insulating material cannot be released outward, resulting in the refractory layer bearing a large compressive impact force. In addition, if the cable is armored, the stress and deformation generated by the steel strip when the temperature changes will also be applied to the refractory layer, which will cause greater damage to the refractory layer and make it difficult to pass the fire resistance test.
Nowadays, wires and cables are needed everywhere, and the probability of disasters is relatively high. Therefore, fire-resistant cables can play an important role in fires. In addition, fire-resistant wires and cables are being vigorously promoted and used in any field.
In addition, to ensure that fire-resistant cables can play a practical role, wire and cable manufacturers must strictly follow the process of making fire-resistant cables to ensure their quality. It is worth noting that the wrapping structure of fire-resistant cables has an impact on their fire resistance performance, and if chosen improperly, it can lead to a decrease in fire resistance performance. From the perspective of cost reduction, non-woven fabric tape can be used as the outer protective layer of mica for non low smoke fire-resistant cables.
How to manufacture winding structures for wires and cables
After the insulated wire core is cabled, it is generally necessary to wrap it with glass ribbon, PVC tape or non-woven tape as reinforcement to keep the structure of the cabled cable round. If the selected wrapping tape is not suitable, it will affect the fire resistance performance of the fire-resistant cable. Using the same number of layers and wrapping structure of mica tape, wrapping non-woven fabric tape or PVC tape after cable formation can pass the fire resistance test, but wrapping coated glass ribbon or mica tape with fire-resistant properties may not necessarily pass the fire resistance test.
The purpose of using coated glass ribbon and mica tape as the cable wrapping layer in the design is to improve the fire resistance of the cable by utilizing their fire insulation and fire resistance properties. However, experimental results have shown that this actually leads to a decrease in fire resistance.