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1. Insulation Damage
After the insulation layer is damaged, the following two conditions may occur depending on the degree of damage:
① Short Circuit: Complete insulation failure will cause a short circuit. During a short circuit, the current through the circuit increases to several to dozens of times the normal operating current. Since the heat generated by the conductor is proportional to the square of the current, the heat value increases drastically, which may cause a fire in a short period. If electric arc discharge occurs during a short circuit, the high-temperature arc may scald nearby personnel or directly ignite flammable materials. Additionally, under short-circuit conditions, some exposed conductors may carry dangerous fault voltages, posing a fatal electric shock risk.
② Leakage: If the insulation is not completely damaged, it will cause leakage, one of the common causes of electric shock accidents. On the other hand, local heating at the leakage point may directly to ignition or further damage the insulation, causing a short circuit and subsequent fire. If the conductor is grounded, although the grounding current is much smaller than the short-circuit current and the heat generated may not ignite the line, the local heating and arcs at the grounding point can still cause a fire.
① Short Circuit: Complete insulation failure will cause a short circuit. During a short circuit, the current through the circuit increases to several to dozens of times the normal operating current. Since the heat generated by the conductor is proportional to the square of the current, the heat value increases drastically, which may cause a fire in a short period. If electric arc discharge occurs during a short circuit, the high-temperature arc may scald nearby personnel or directly ignite flammable materials. Additionally, under short-circuit conditions, some exposed conductors may carry dangerous fault voltages, posing a fatal electric shock risk.
② Leakage: If the insulation is not completely damaged, it will cause leakage, one of the common causes of electric shock accidents. On the other hand, local heating at the leakage point may directly to ignition or further damage the insulation, causing a short circuit and subsequent fire. If the conductor is grounded, although the grounding current is much smaller than the short-circuit current and the heat generated may not ignite the line, the local heating and arcs at the grounding point can still cause a fire.
2. Poor Contact
Connection points are the weak links in electrical circuits. If the connection points have poor contact, the contact resistance increases, which 必定 (inevitably) causes increased heating at the connection points, even generating dangerous temperatures that can become ignition sources. If the connection is loose, it may discharge and ignite, forming an ignition source.
In particular, for connections between copper and aluminum conductors, if a copper-aluminum transition section is not used, they can easily become ignition sources after a period of use. In humid environments or outdoors, aluminum and copper conductors cannot be directly connected and must use a copper-aluminum transition section.
In particular, for connections between copper and aluminum conductors, if a copper-aluminum transition section is not used, they can easily become ignition sources after a period of use. In humid environments or outdoors, aluminum and copper conductors cannot be directly connected and must use a copper-aluminum transition section.
3. Severe Overloading
Overloading accelerates insulation aging. Excessive or prolonged overloading can cause the conductor to overheat, creating a fire hazard. Additionally, overloading increases the voltage drop in the circuit. The main causes of overloading are: ① Users arbitrarily connecting numerous electrical devices, to overloading.
4. Broken Conductors
A break in the conductor can cause various accidents such as grounding, intermixing of lines, or short circuits. If a broken conductor falls on the ground or a grounding conductor, it may cause electric shock. Sparks generated when a conductor breaks or is pulled apart, as well as sparks from swinging overhead conductors, can ignite adjacent flammable materials. Furthermore, the disconnection of one phase in a three-phase circuit can cause unbalanced operation of three-phase equipment, potentially burning out the equipment; disconnection of the neutral point (working neutral wire) can also cause unbalanced three-phase voltages in the load, damaging electrical equipment.
5. Inadequate Clearance and Improper Protection
The common issue in circuit installation is inadequate clearance, which can to collision short circuits, electric shocks, leakage, and hinder normal operation. Inadequate clearance is mainly caused by three factors: ① Poor construction quality, such as not strictly following design standards and installation specifications; ② Improper operation and maintenance or long-term lack of maintenance; ③ Some personnel disregarding existing electrical equipment and violating technical regulations during risky construction.
