Teach you what is a fire-resistant cable


The problem of casualties after many electrical fire ac […]

The problem of casualties after many electrical fire accidents is caused by the sudden interruption of the power supply of the circuit system. Therefore, it is very important to use fire-resistant cables in the circuit to keep the wire loops in the event of a fire, and it can be normally powered within a certain period of time. So how much do you know about fire-resistant cables?
Refractory cable: It means that the cable can maintain normal operation in a flame for a certain period of time, that is to say, it still has a certain time power supply capacity under the flame.
In China, according to the flame temperature level, refractory cables are divided into A and B categories.
Class A is a flame that can burn for 90 minutes at rated voltage at a flame temperature of 950 ° C-1000 ° C without breakdown. Category B is that the cable can be burnt for 90 minutes at rated voltage at a flame temperature of 750 ° C to 800 ° C without breakdown.

In fact, Class A and Class B are just ordinary fire-resistant cables. The best fire-resistant cables are mineral insulated fire-resistant cables composed of copper core, copper sheath and magnesium oxide insulation materials. Because the fire-resistant layer of ordinary fire-resistant cables is composed of inorganic materials and general organic materials, and the fire-resistant layer of mineral insulated fire-resistant cables is entirely composed of inorganic materials, therefore, the fire resistance is superior to ordinary fire-resistant cables. And it can work in a long-term environment at a temperature of 250 ℃. At the same time, the mineral insulated cable also has the characteristics of explosion-proof, corrosion resistance, radiation resistance, strong mechanical properties, long life, no smoke, no harmful substances and so on.
However, due to the high price of the cable, the complicated production workmanship, and the difficulty of installation, it is possible to choose this kind of cable with high mineral insulation and fire resistance in the occasions where major public buildings, gas stations, etc. have sufficient economy and high fire resistance requirements.

Let you know that when choosing a refractory cable, you should pay special attention to the following points:
1. When used in places where the cable wiring density is concentrated and large or major public buildings, next to gas stations are prone to fire, mineral insulated or Class A fire-resistant cables should be selected. In other cases, Class B can be selected according to the fire resistance requirements of the occasion.
2. Most of the fire-resistant cables are used in the power supply circuit of the backup power supply to ensure that this circuit can operate normally in the event of a fire.
3. According to the length of the power supply circuit, select the appropriate fire-resistant cable specifications. In order to prevent the rapid rise in temperature when a fire occurs, causing circuit transmission problems, you should choose a fire-resistant cable that is at least twice the size of the original fire-resistant cable model.
4. The refractory cable only maintains normal operation under flame for a certain period of time, and cannot be used as a high temperature resistant cable.
5. In order to reduce the probability of failure of the cable joint in the fire, the number of joints should be reduced as much as possible during installation. If it must be used as a branch wiring, the joint part should also be fireproofed.