How to effectively prevent LED street light leakage accidents?
March 24, 2023
So far, there is still no consensus in the industry on how to prevent street lamp leakage and injury accidents. However, by taking some active prevention and control measures, the occurrence of such situations can be minimized or avoided. 1. Leakage situation analysis
The majority of street lamp leakage injuries are "indirect contact" with light poles, water or other auxiliary parts that are not charged. (1) Water accumulated on the road makes the cable (wire) joints soaked directly or indirectly
1. Soak in water directly. There are protective fuses or circuit breakers installed in the access door at the bottom of the light pole, and there are generally no strict waterproof measures (IP67 and above), and serious leakage will occur when the water level reaches the wire and its connection. 2. Indirect immersion in water. Some of the cable (line) branch joints for power supply to each street lamp are in the maintenance shaft next to the light pole (below the horizontal ground), and some are in the maintenance door at the bottom of the light pole. The traditional waterproofing method is to wrap it with self-adhesive tape (commonly known as waterproof tape). If the workmanship is not done well, or the degree of insulation is significantly reduced over time, electricity will leak when it is immersed in water. In addition, if the insulation layer of the buried cable is damaged during green planting, replacement of seedlings or other excavation construction, it will also be thirsty for electricity when the surface is flooded. Direct or indirect immersion of wire (cable) joints is the main cause of street lamp leakage and injury. (2) Aging of the insulating layer
There are cable (wire) connectors inside the light pole inspection door, usually wrapped with insulating tape (cloth), which will age after a long time, especially in a humid environment, when the connector is very close to the light pole wall or directly against the light pole wall , there may be a leakage. (3) Lamps and electrical appliances are damaged
When the lamps and appliances are damaged and leak electricity, the maintenance door at the bottom of the lamp pole or the fuse, circuit breaker or leakage protector inside the lamp will be automatically disconnected, so this kind of injury is less. (4) Others
Street lamp wiring system leakage, in addition to the above common types, there are other situations.
2. Prevention measures
(1) Defense
1. Install residual current action protection device (leakage protector, etc.)
In the vast majority of street lamp leakage accidents, the leakage is formed by water or a failed insulating medium, and the intermediate resistance is large, which is not enough for the circuit breaker in the distribution box to form an overcurrent trip protection. At present, to solve such problems, installing residual current operating protection device is the best way. The installation of residual current operating protection devices in low-voltage power distribution systems is one of the effective measures to prevent electric shock accidents caused by direct and indirect contact." Residual current operating protection devices. The street lamps have a large area and a large number. The line situation is very difficult. Therefore, it is the best choice to install an unattended residual current action protection device for protection, especially when there is a sudden heavy rain. The leakage protection device is not installed, and the water on the road makes the street lamp leakage Injuring people may be caused by the management personnel not having time to turn off the power switch, or it may be due to luck that they did not deal with it. 2. Problems and solutions of installing residual current action protection device
(1) Frequent tripping
In the low-voltage power supply system, in order to reduce the scope of power outages caused by personal electric shock accidents and ground fault cut-offs, the residual current action protection device should adopt hierarchical protection, two or three levels, and the action current value and action time should be coordinated to achieve It has action selective protection; hierarchical protection is also one of the measures to prevent personal electric shock accidents caused by ground faults in distribution lines. The underground cables of street lamps are long, and there may be a weak leakage current to the ground; the cable forms a small capacitance to the ground, and there may be a small leakage current. Therefore, the "first-level protection" residual current operating protector installed at the head end of the branch cable in the distribution box should reasonably select the rated operating current according to the line length of its load, line environment and cable quality, 100mA , 200 mA, 300 mA. A small leakage protector is installed inside the light pole, which only protects a single light pole. It belongs to "end protection". The rated operating current should be 30mA. In this way, the problem of frequent tripping of the line is solved to a certain extent. If a residual current operating protection device with a large rated operating current is installed and still trips, it means that there is a serious fault in the line, and a thorough overhaul or replacement is required, otherwise, electric leakage accidents may easily occur. Of course, in the case of ensuring normal lighting, it is recommended that the rated residual operating current of the "level one protection" be set smaller, so that the safety is higher. (2) Responsibility for installation or not
The installation of residual current operating protection device is a supplementary protection measure in addition to the zero connection or grounding protection of the system, focusing on prevention. Therefore, in case something goes wrong, it will not be held accountable because of the installation of the residual current operating protection device. Outdoor electrical installations should be equipped with residual current action protection devices, and power supply lines and equipment installed in water should be installed with residual current action protection devices (road water, street lamps, etc.). (3) Whether the graded protection can effectively prevent electric leakage accidents
Leakage protection devices were originally produced to protect human life, but there are very few cases where they are actually used to directly protect people (tripping when people touch electrified objects), and most of them are used for prevention. Due to line aging, equipment damage, sudden changes in the surrounding environment, etc., light poles, road ponds and other objects that should not be charged are temporarily charged, and the first-level (superior) leakage protection device with a rated operating current of several hundred milliamperes will trip immediately. Even if someone later wades in the fault area or touches the light pole, no accident will occur. A non-delay leakage protector with a rated leakage action current of 30 mA is installed in each light pole, mainly to protect live maintenance workers, temporarily isolate a single light pole for easy maintenance by the staff, and automatically isolate a single overcurrent or leakage Light poles (to avoid tripping of superior protection), etc. (2) Governance
The residual current action protection device is easy to trip, a small part of the reason is that the main cable has a slight leakage to the ground, and most of the reasons are that the cable (wire) connector is not standardized or aging. 1. Clarify design requirements, optimize design schemes, and improve design standards
(1) The construction design description of the actual drawings often has such a discussion: refer to or follow a certain atlas or a certain specification. Many of the construction teams who installed street lamps were not professional, and the drawing design did not have clear and specific requirements. He did it based on his own experience, and did not check any atlases or specifications at all. Also, a description like "cables are laid along roads and rocks" is too general. Unclear and fuzzy construction design instructions often lead to irregular construction and leave some safety hazards. If the cable burial position deviates greatly, it is easy to be damaged by greening or other construction excavations. (2) The traditional practice of street lamp engineering construction: the main cable is cut off to enter the lamp pole, and it is recommended to use a special waterproof connector with good waterproof performance and long life (3) With the continuous advancement of technology, many new materials have gradually appeared in the construction of street lamps, with strong waterproof ability and long service life, such as glue-filled waterproof junction boxes, high waterproof grade distribution boxes, waterproof terminal blocks, etc., when designing It can be used in part or in full according to the construction funding situation. If the waterproof measures of the line are done well, the street lights can still operate normally during the flood season. Occasionally, I saw a TV screen showing that the water on the road had passed the waist of an adult, but the street lights were still on. It can be seen that the waterproof circuit of the street lights in the road section is well done. 2. Strengthen the construction supervision and acceptance of street lamp projects
Street lighting projects are generally ancillary projects of roads, which are often subcontracted in whole or in part, and the quality cannot be guaranteed. Therefore, it is necessary to strengthen the management of project supervision and completion acceptance. 3. Do a good job in maintenance and repair
A long-term mechanism should be established for daily inspections, daily inspections, key maintenance, and regular inspection and maintenance of street lamps to continuously improve quality and standards. Ordinary cable (wire) joints have a limited lifespan and must be removed and repacked regularly, otherwise, electric leakage may occur and a trip may occur. During maintenance and repair, don`t try to save trouble and turn a blind eye to small problems, let alone cover them up deliberately, thinking that it`s enough to turn on the lights, because small problems may also cause electric leakage and hurt people. Inadequate and irregular maintenance management is an important reason for many street lamp leakage accidents. 3. Overview
One of the most effective measures is to install a residual current action protection device to prevent street lamp leakage accidents to the greatest extent. According to the length of the line and the actual operating conditions, the reasonable setting of the hierarchical protection of the line can not only effectively prevent the occurrence of electric leakage accidents, but also significantly reduce the frequency of non-fault trips. Only by improving the design level, standardizing construction behaviors, and strengthening maintenance and repairs, can street lights be safer and more reliable. The above content is provided by WOSEN. WOSEN is a professional manufacturer and supplier of Led Flood Light, Led Street Light, Led Solar Light, etc. For more information, please visit https://www.wosenled.com/ or contact admin@wosenled.com or WhatsApp +86-13425434349
