What Are the Misunderstandings in Cable Installation and the Causes of Heat Generation?

Ⅰ. What are the misunderstandings in installation of electrical power cable?

1. Regardless of strong and weak electricity, direct co-pipe installation

It is reported that AC power is commonly used in our family, which is divided into strong and weak, and should be accommodated differently when connecting wires. However, in the actual cable installation, some construction teams directly put all the wires together for the convenience of construction, and the power cords, network cables, telephone lines, etc. are all placed in the same bottom box. The result of this is that there will be interference between the lines, resulting in unstable signals, and even serious fires will bury hidden dangers.

2. The cable is installed directly without casing

In order to cut corners, some irresponsible construction parties bury the wires directly in the wall during the installation of electrical power cables. The wires are not covered with insulating tubes, and the wire connectors are directly exposed, so that the cables cannot prevent external damage, such as in the future. In daily life, the cable is bitten by rats due to lack of casing protection, or is damaged by moisture or external force, which makes the power cable short-circuit when in use, and even causes safety hazards such as fire.

3. Duplicate wiring

Generally speaking, the line should be made into a "live line", and the wires of the same direction should be placed in a pipe without exceeding 40% of the pipeline capacity. This is economical and avoids future maintenance. trouble. However, in the actual cable installation and construction, some construction workers use one pipeline for each wire in order to make the pipeline look clearer. In this way, a lot of pipelines are buried inside the wall, which is also for future maintenance. This brings trouble, especially the difficulty in finding the location of the problematic pipeline. It is necessary to destroy most of the wall and ground structure before finding the problem, which increases the difficulty of future maintenance.

4. Socket wires can be installed at will

The power wire must use copper wire. However, in the actual cable installation, some people prefer to use aluminum wire. Because aluminum wire is easy to oxidize, the joints are easy to ignite, and the incidence of electrical fires is dozens of times that of copper wires.

Ⅱ. The reason for the heating of the electrical power cable

1. The cable conductor resistance does not meet the requirements, causing the cable to generate heat during operation.

2. Inappropriate cable selection, resulting in too small conductor cross-section of the cable used, and overload during operation. After a long time of use, the heating and heat dissipation of the cable will be unbalanced, resulting in heat generation.

3. When the cables are installed too densely, the ventilation and heat dissipation effect is not good, or the cables are too close to other heat sources, which affects the normal heat dissipation of the cables, and may also cause the cables to generate heat during operation.

4. The joint manufacturing technology is not good, and the crimping is not tight, resulting in excessive contact resistance at the joint, and heating of the cable.

5. The insulation performance between phases of the cable is not good, resulting in low insulation resistance and heating during operation.

6. The partial sheath of the armored cable is damaged, which will cause slow damage to the insulation performance after the water enters, resulting in a gradual decrease in the insulation resistance, and will also cause heating during the operation of the cable.

After the power cable generates heat, if the cause is not found and the fault is eliminated in time, the insulation thermal breakdown phenomenon will occur after the cable continues to be energized. It may cause a short circuit trip of the cable, which may cause a fire. So we must pay attention to it.