With the rapid development of China's economic construction, various buildings, especially high-rise buildings, are increasing. In the event of a fire, power failure, or other disaster in these buildings, emergency lighting facilities shall be provided to ensure the safety of personnel in the building and the smooth progress of fire rescue work. At present, the provisions on emergency lighting in the existing design standards are not specific enough. The comprehensiveness, specificity and scientific nature of the operation need to be further explored and improved. It is also necessary to add new content to supplement it. More engineering designers are involved in the practice. Through many years of engineering design, the author has made some explorations and discussions on emergency lighting. I am writing this article for reference.
First, the scope and requirements of emergency lighting
The design content of emergency lighting for civil buildings includes two parts of accident lighting and evacuation lighting (excluding safety lighting - the same below).
(1) Accident lighting
Lighting that is set to avoid personal injury or death and that can continue to maintain important work when an accident occurs is called accident lighting. Civil buildings need to be designed with accident lighting to maintain normal power failures. Accident lighting is permanently placed in substation, fire control room, generator room, fire pump room, communication hub, cash register and valuable commodity sales area. For places that need to continue to work, the illumination of accident lighting should not be lower than the illumination value of normal lighting, and the illumination of general accident lighting should not be lower than 10% of normal lighting. Accident lighting should be uniformly arranged in combination with normal lighting, usually using part or all of the normal lighting as accident lighting, and power conversion when the fault occurs. Accident lighting should use light source that ignites fast, reliable and high luminous efficiency, such as incandescent lamp, straight tube fluorescent lamp or compact fluorescent lamp with fast ignition, instead of high-intensity gas discharge lamp, such as high-pressure mercury lamp, high-pressure sodium lamp and metal. Halide lamp.
(2) Evacuation lighting
Illumination used to guide people to evacuate when various accidents occur is called evacuation lighting. Evacuation lighting includes an "exit sign light" that marks the exit location and a "pointing sign light" that directs the exit, and an "evacuation light" that is used to meet the evacuation channel illumination requirements. When the normal power supply is cut off, the evacuation sign should be visible to anyone on the evacuation channel or in a public place. The exit sign lights shall be installed in the normal exit and emergency exit of the building leading to the outdoor, the doorway leading to the evacuation stairwell or the front room of the anti-smoke stairwell, and the exit of the public place leading to the evacuation walkway. The pointing sign light shall be placed at the corner of the corridor or on the straight section of the corridor no more than 15m away from the exit sign light. In order to avoid the effects of smoke during a fire, the exit sign light should not be overcharged. The exit sign light should be installed above the inside of the exit door. When installed on one side of the door, the height from the ground should be 2.0m~2.5m. When the pointing sign light is suspended under the ceiling, the height from the ground should be 2.2m~2.5m; when installing on the wall, the height from the ground should not be greater than 1.0m. The average illumination of the evacuation illumination on the ground line of the evacuation channel should be no less than 0.5 lx. In the design, the pointing light and the exit sign light are often used as part of the evacuation lighting; when the illumination requirement is not met, the evacuation lighting should be arranged in coordination with the normal illumination of the aisle (a part of the normal lighting can be used as the evacuation lighting in the stairwell). Floor marker lights can also be used as evacuation lighting). In order to simplify wiring and control, the lighting in corridors and stairwells in buildings with higher grades can all be designed according to evacuation lighting requirements.
The layout of the evacuation lights shall be installed at the intersection of the walkway, the corner, the evacuation stairwell, the smoke-proof stairwell and the front room, the front room of the fire ladder, the evacuation walkway and the fire alarm button and fire-fighting facilities.
Second, emergency lighting power supply
If the normal lighting power supply fails, the conversion time between accident lighting and evacuation lighting to emergency power supply should not exceed 15s, and the emergency lighting power supply should not be less than 30 minutes. In actual engineering design, the emergency lighting power supply should be determined according to the type of building and the possible power supply. The types of emergency power supply are generally:
(1) Power system effectively separated from normal lighting power supply
When the building is powered by two high-voltage power sources and two or more transformers are installed, emergency lighting and normal lighting should be connected to different transformers respectively; when the building has only one high-voltage power supply, the emergency lighting power supply is nearby. It is obtained from a substation powered by another high voltage power supply.
(2) Diesel generator set with self-starting function
When the building is equipped with such a diesel generator set and the total time of start-up and conversion is not more than 15 s, the emergency lighting should be separated from the electrical load and supplied by a separate distribution circuit.
(3) Self-contained battery packs in the emergency lighting or outside the lamp
Usually this method is used for the backup power that cannot be obtained by the power grid, the building floor is not too high, the number of emergency lights is not large or the installation is scattered.
Third, emergency lighting control and wiring
Emergency light wiring
In order to ensure that the emergency lights are ignited in the event of a fire or other disaster in the building, the wiring of the emergency lights must be correct.
The control of emergency lighting is determined by its mode of operation. Hotel buildings, high-rise residential buildings and other buildings are inaccessible day and night. The evacuation lighting should be in continuous operation. The emergency lights should be directly connected to the emergency lighting circuit. The switch that controls the on/off switch is not installed, or the two-lead self-contained battery is used. The emergency lighting is connected to the normal normal lighting line.
In the malls, restaurants, multi-purpose halls, fitness and entertainment halls, etc., there is no access during non-business hours. In order to save electricity, evacuation lighting can be turned off at this time. Therefore, it can be used in the fire control room, guard duty room and The total service desk is centrally controlled, or the opening and closing of the evacuation lighting is controlled in the duty divisions of each department. When using emergency lighting with battery, three-lead wiring should be used, so that the battery in the emergency light is often charged. The functions and wiring of the general two-lead and three-lead emergency lighting fixtures are shown in the above table.
At present, some manufacturers have produced four-lead and five-lead emergency lighting fixtures, which provide a switch that can be set to switch the emergency light source between the emergency light source and the battery pack. The author believes that this is not advisable, so it is easy. Causes operational errors. If you do not pay attention to resetting the switch after disconnecting or disconnecting, it will not ignite the emergency light in an emergency.
Fourth, the laying of emergency lighting lines
The emergency lighting circuit shall be such that it does not affect the use of emergency lighting in the event of normal lighting power failure or in the event of a fire. Therefore, in addition to the emergency lighting distribution box should be set separately from the normal lighting distribution box and placed in a place without fire hazard, the emergency lighting line and the normal lighting line should not share the neutral line, nor should it be worn in the same protection tube. Laying.
The branch lines of emergency lighting shall be divided according to the fire compartment. It is not suitable to cross the fire compartment. The power distribution trunk of emergency lighting may cross the fire protection zone. Insulation and fire prevention measures shall be taken when crossing.
The line should be made of flame-retardant wire or cable, or ordinary wire or cable, but it should be protected by metal pipe or hard-burning hard plastic wire tube. When it is dark, it should be laid in non-combustion body. It should be less than 30mm. For example, the fireproof coating such as acrylic latex should be applied to the outer wall of the metal pipe.
The laying of emergency lighting lines on electric shafts and cable trays can be clearly applied without the need for pipe protection. However, flame-retardant wires and cables with non-combustible materials and insulation should be used. Cables shall be protected by metal pipes when passing through walls and floors. The pipes shall be sealed between walls and floors, and the pipes shall be filled with non-combustible materials.
Fire-rated cables are only considered for trunk lines that supply emergency lighting in buildings that are particularly important.
Emergency lighting is one of the most common, most commonly used, but very important design contents in engineering design, and needs to be further explored and summarized in practical work. In addition, due to the uneven quality of emergency lighting products for civil buildings, some are only furnishings. Once a fire occurs, it is difficult to play a role. Therefore, the production and use of emergency lighting products should be strictly supervised and managed to make them further perfect and reliable.
5. Technical requirements for self-contained power supply emergency lights
(1) Battery: It is required to use a fully enclosed, maintenance-free, small-sized rechargeable battery. Generally, a cadmium-nickel battery should be used. The lead-acid battery is superior in conditions, but the size is large and the life is short, but the car should not be used. The battery is not allowed to use the original battery.
(2) There should be inverter, control, protection and charging. Generally there should be overcharge protection. For lead-acid batteries, over-discharge protection must also be provided. As for cadmium-nickel batteries, the effect of over-discharge is small.
(3) The inverter circuit shall ensure a certain lumen efficiency. That is, the ratio of the luminous flux output by the light source after switching from the normal power supply to the battery supply. For non-continuous operation emergency lights, the luminous flux after switching to battery power supply 5S is not less than 80% of its rated luminous flux.
(4) The voltage at the end of the battery discharge should not be lower than 80% of the rated voltage. Some countries have a higher percentage. At the end of the discharge, it should be the end of the emergency continuous working time specified by the emergency light.
(5) Manual operation switches shall not be installed between the battery pack and the light source in the emergency light. The normal power side of the emergency light should be equipped with short-circuit protection; in addition, there should be a charging indicator and a test button.
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