The integrated wiring manufacturer Weikang found that the wire is mainly insulated by the outer layer of the sheath. It is corroded by the outside air for a long time, and the insulation performance is gradually reduced. It gradually ages and becomes hard, brittle or falls off. At this time, it cannot be insulated. The insulation of the exterior of the household wire is mostly made of plastic and rubber. When it is used for a long time, it will age and lose its insulation. General household wire normal service life can reach 10-20 years. After the wire is aged, the insulation performance is degraded, and a short circuit is likely to occur. Especially in the case of wet weather, although the appearance of the wire is intact, the insulation performance has been lowered, and a short circuit occurs when the water is immersed in the metal conductor to cause a fire.

 

 

1. External force damage. From the analysis of operation in recent years, especially in Shanghai Pudong, where the economy is developing at a high speed, quite a number of cable failures are caused by mechanical damage.

 

2. Insulation is damp. This situation is also common and generally occurs at cable joints in direct buried or drained pipes. For example, if the cable joint is not qualified and the joint is made under humid climatic conditions, the joint will be filled with water or mixed with water vapor, which will gradually damage the insulation strength of the cable and cause malfunction.

 

3. Chemical corrosion. The cable is directly buried in the acid-base area, which often causes the cable armor, lead or outer sheath to be corroded. The protective layer is chemically corroded or electrolytically corroded for a long time, causing the protective layer to fail and the insulation to be lowered. Cable failure.

 

4. Long-term overload operation. Overload operation, due to the thermal effect of the current, the load current will inevitably lead to the conductor heating when passing through the cable. At the same time, the skin effect of the charge and the eddy current loss of the steel crucible and the loss of the insulating medium will also generate additional heat, thereby increasing the cable temperature. Excessive temperatures during the long-term overload operation accelerate the aging of the insulation and the insulation is broken down. Especially in the hot summer months, the temperature rise of the cable often leads to the breakdown of the cable insulation first, so in the summer, the cable failure is particularly high.

 

5. The cable connector is faulty. Cable joints are the weakest link in cable lines, and cable joint failures caused by direct personnel failure (poor construction) often occur. During the process of making the cable joints, the construction personnel may cause the insulation of the cable head to be lowered if the original network is not tightly crimped or insufficiently heated, thus causing an accident.

 

Handling line aging issues:

 

1) There are some bare wires.

 

2) Some wires are against the wall and are damaged.

 

3), to replace the electric knife with a common standard knife.

 

4), to replace the indoor lamp head and wire, all the bedside switch is a pull switch.

 

5) To regulate the use of electricity management, eliminate potential safety hazards, and eliminate the occurrence of electricity theft

 

6), lack of necessary monitoring of the danger points of electricity use

 

7), leakage protector installation loophole

 

8) Construction enterprises should earnestly strengthen the training on the safety production education and safe use of electricity for employees, and enhance employees' awareness and ability to prevent electric shock and self-safety protection. In particular, it is necessary to strictly implement the system for the certification of electrical workers.

 

9) For the electrical equipment and insulating tools on the construction site, the qualified electrical test department shall be regularly sent to conduct relevant electrical preventive tests such as DC resistance, grounding resistance, insulation resistance, withstand voltage and leakage.

 

10) It is necessary to educate and guide the electricians at the construction site to learn and master the "Electricity Safety Work Regulations" and "Low-Voltage Safety Work Regulations". Do not carry out live work at will. Insulation protection should be taken and the guardian should be arranged to operate.

 

11) Pay special attention to the safety distance between the construction site and adjacent overhead and laying power lines to avoid metal objects such as steel bars, water pipes and tools from touching high and low voltage wires. It is not uncommon for electric shock and casualties to occur in this category. Therefore, special attention should be paid to prevention and monitoring.

 

12) Strengthen daily inspections. Whether the leakage protector is effective, whether the melt rating and the setting value of the circuit breaker are correct, whether the grounding lead and the PE wire of the electrical equipment are connected well and reliable, etc., should form a regular and irregular inspection maintenance management system and accountability system, effectively strengthen Inspection supervision.