Lighting protection of architectural lighting systems

1 Current Fire Code Regulations for Fire Protection and Insulation of Architectural Lighting Systems Current fire safety technical regulations and electrical fire safety management regulations generally have certain requirements for the fire protection of architectural lighting systems. The original provisions of the regulations can be found in the reference literature. The relevant contents of the specification are summarized as follows: (1) In order to prevent the radiation heat hazard, the luminaire must maintain a fire safety distance from combustibles and keep away from combustibles; (2) The switch, socket, and luminaire (including ballast) are all It should not be directly installed on flammable structures and flammable decorative materials. If it is necessary to install it, it must be insulated and heat-dissipated. (3) The wiring corresponding to the luminaire should not be applied directly to the decorative materials of walls and skirts. Even if the wiring has mechanical protective protection, it should also take appropriate fire protection measures before laying. The plywood used for roof and wall decoration is used as an example. To prevent roof and wall plywood from being damaged due to thermal failure during the installation of switches, sockets, and luminaires, the inner and outer surfaces of the plywood and the corresponding wooden keel should be coated with fireproof paint, or Before the decoration, it should be treated with flame-retardant impregnation, and it should meet the requirements of Class B1 combustion performance. Even lighting materials cannot be lower than B1. These requirements are the experience crystallization of the fire lessons, play a role in guiding the lighting system to prevent fire and ensure the safe operation of the lighting system.

2 Electrical fire hazards often found in on-site electrical fire detection.

2.1 The safety distance between the luminaire and flammable materials is not enough. The visual inspection method can be used to easily find that the luminaire power exceeds the limit value. The fire safety gap between the high temperature surface and combustible materials does not meet the requirements. Some sockets and switches are installed on the On the side of the window, it is easy to be covered and shaded by the curtain cloth. The high-powered luminaire is too close to the flammable material, and some mobile appliances are improperly placed. For example, in a research institute in May 1985, the surface of the ceiling of the darkroom in the microwave laboratory was covered with a layer of flammable absorbing material, and the long-term lighting of the lighting fixture was overheated and smoldered. Another example is the operation department of a certain city of plastics industry company in October of 1986, because the ballast of the fluorescent lamp overheats, ignites the close flammable material, then extend to plywood wooden keel roof. The Karamay Friendship Auditorium in Xinjiang in Xinjiang burned the screen with high-temperature lighting fixtures, and more than 300 people died. In addition to solving these problems through engineering measures, most of them can be resolved by strengthening electrical fire prevention management and electrical fire safety education, and improving employees' awareness of daily electrical fire prevention.

2.2 Insulation and Heat Dissipation Measures are not standardized The most problems detected at the site are those problems that are difficult to rectify after the project is completed. Insulation, heat dissipation and fire prevention measures are not implemented in the project. Sockets are placed on flammable materials or flammable decorative materials. They are mounted on the bottom of the socket box and around the concealed socket box. Some are made of glass cloth, some are made of asbestos mats, and thermal insulation is used. For ceiling mounted fluorescent screens, spotlights, downlights, etc. embedded in the ceiling mounted luminaires, the usual method of treatment is to put the lamp line through the high-temperature yellow wax tube, and some even with the glass fiber cloth together with the lamp box and the transformer package. The installation of these lamps and lanterns on the ceiling is more complicated. Because it is a potential source of electrical fire, it must heat up during normal operation, and some luminaires have high temperatures, and transformers are used in conjunction with them. Now take the spotlight as an example, the spotlight transformer is installed in the ceiling, the secondary rated voltage is only 36V, the bulb current is large, the temperature is high, and some can reach 300°C. That is, the surface temperature of the lampshade is also generally ranging from 90°C to 160°C. Some of them can reach about 200°C. Sometimes the plywood near the shell is baked and carbonized. In the product structure, some spotlight structures are not standardized. The lamphead box is separated from the transformer. The low-voltage wires are not resistant to high temperatures. The lamp wire is not heat-resistant and the pipe is not in place. The heat-insulating electrician uses asbestos cloth to enclose it together. Can play a role in insulation, but also ignored the heat radiation lamps, the danger is that the internal heat may be concentrated, resulting in local human overheating, causing fire hazards. There are also put the neon transformer in the sealed ceiling without inspection hole, the transformer itself is a heating element, long-term shelved in the ceiling, even if there is usually a thermal failure is not easy to find, electrical fire detection is not good . 2.3 Renovation materials in the direct wiring route hidden dangers Many plastic or soft cables were laid directly in the decoration materials, and some were made of steel pipes, but they were not in place so that the wires were exposed outside, and some were used because of inconvenient construction. Snake skin tube instead of steel pipe. One of the reasons is that the level of electrician technology is poor, and the other reason is that the owners do not pay much attention or consider it economically, but neglect the work of electric fire safety. 2.4 The placement of the luminaire destroyed the fireproof performance of the ceiling. The installation of the ceiling luminaire caused damage to the fireproof performance of the ceiling. This did not attract the attention of the relevant departments. We can see the function of the building according to the indoor use, and the owners everywhere. As for the requirements of indoor lighting and lighting effects, many kinds of lamps and lanterns of various types are installed on the ceiling. The installation of these lamps requires digging holes in the ceiling. The result of the digging can undermine the integrity of the fire protection and sound insulation measures of the ceiling. And effects. In the event of a fire, smoke and flames spread across the gap and spread over the ceiling. Through the gable holes and neighbors, the area of ​​fire is expanded. Even if non-flammable materials or non-flammable materials are used on the ceiling, the penetration gap and spread of smoke and flame are also in the Inevitably. For smoke and flame penetrating ceilings, according to foreign data, in a ceiling test with a one-hour fire-resistant time for the installation of an embedded lighting device, the luminaire has a plexiglass disk within 28 seconds of ignition. Burned, the flame passed through the plexiglass plate embedded in the lighting and entered the upper part of the ceiling in 2 minutes. The holes and the gaps significantly reduced the fire-resisting time of the ceiling. The installation of the luminaires not only buries the electric ignition source on the ceiling, but also leaves a hole in the ceiling, which provides a passage for the spread of fire on the ceiling. This must attract the attention of all parties and take measures to prevent it.

3 Fire and heat protection measures available for reference The following is a description of some relevant materials in the United Kingdom. To solve the spread of pyrotechnics caused by holes in the ceiling of lighting fixtures, some simulation experiments on fireproof and heat insulation of ceilings are now excerpted. As follows, can be used as a reference for thermal insulation and thermal protection measures

3.1 Fire Tests on Fireproof Ceilings for 30 Minutes In order to study the situation where smoke and flame penetrate the ceiling through the gaps of lighting fixtures and prevent smoke and flame from causing unnecessary damage to persons outside the ceiling, Trade did not take protective measures against them. A small fire test was performed on the ceiling of the lighting device. The test results showed that after only five minutes of ignition test, smoke and flame penetrated the ceiling and entered the cracks in the floor above. After 15 minutes, the test device was completely covered by smoke. The tests showed that the installation holes of the lighting device did destroy the fireproof performance of the entire roof, and the fireproof time was less than 30 minutes and it was penetrated by smoke and flame. Since the object of this test is only a simulated test device, if it is not a simulated test device but a real living environment space, deadly smoke and flames will quickly fill the room above the ceiling, resulting in unnecessary casualties. And property loss.

3.2 Fire test on 60-minute fire-resisting ceiling The British Loss-Fire Commission conducted an independent 1-hour fire test on the ceiling in accordance with British Standard 476 Part 21, 1987. As a result, there was no ceiling lighting fixture. In the case of protective cover installation, the roof is destroyed within a few minutes, and smoke and flames enter the upper space of the ceiling and the room upstairs. The results of this test show that the lighting device equipped with a protective protective cover ceiling can achieve a flame retardant protection performance of 60 minutes, and can maintain the integrity and stability of the roof insulation and fire resistance.

3.3 Application of Different Types of Roof Structures Test Conditions In order to give readers a complete understanding of the tests, the test conditions for different roof structures are listed below.

3.3.1 Testing of gypsum board ceilings In accordance with the general procedures and standards of BS 476 Part 21 of 1987, on 3 December 1996, the Inglag protective protective cover for lighting installations on the ceiling of a 4500mm x 3500mm load-bearing gypsum board was put on the roof. Live, flame-retardant test on the protective cover of the lighting device. Test results Safeguards, adiabatic time and load-bearing capacity all reached the fire endurance limit of 60 minutes.

3.3.2 Test of suspended ceiling type (pendent type) ceiling In April 10, 1992 According to the general procedure and standard of BS476 part 20 of 1987, Inglad protective protection for lighting devices installed on ceiling type ceilings. The hood was subjected to a flame-retardant protection test, and the test result reached a fire resistance limit of 67 minutes.

3.3.3 Tests on Concrete Roofs On July 6, 1994, flame retardant protection of Inglars Lighting Protective Covers installed on concrete ceilings was performed in accordance with the general procedures and standards of BS 476 part 22 of 1987. The test, fire resistance reached 61 minutes.

3.4 Ingram's application of flame-retardant products Inglef has developed fire-retardant cages and protective covers for lighting devices to choose from. Fireproof cages are made from lighter stencils and internal fixation with expanded material; protective covers can be made by filling glass fabrics with water-based intumescents. All of them can reach the fire endurance limit of 60 minutes. In use, they do not affect the ventilation, heat dissipation, and heat insulation and sound insulation of the ceiling.

4 China's lighting system fire protection measures and product development From the front to see China's fire protection technical specifications on the lighting, switches, sockets, heat insulation, heat treatment issues have been stipulated, but because of heat insulation, cooling measures have not yet achieved a Consensus fire-retardant products are available for selection. Therefore, the results of operation and implementation at the construction site are neither uniform nor standardized, and they can be seen on the site in various ways, even in a variety of processing results. For the local holes left by the installation of the ceiling lighting device, the overall fireproof performance of the ceiling is not taken into account in the event of a fire. This provides a passage for the spread of flames and smoke, leaving electric hazards in the building. In the detection of electrical fire safety, the determination of hidden dangers in electrical fire and the formulation of corrective plans by the owner have also increased the difficulty of implementation. The technical specifications for fire protection and the related regulations on electrical fire prevention stipulate that the fire safety distance between the high-temperature surface of the luminaire and combustibles and the provisions for the wiring of flammable decorative materials have been stipulated very clearly and specifically. As long as the strengthening of electrical fire prevention management, strengthening of electrical fire education, improve electrical fire safety awareness, and strengthen fire supervision and management can be resolved. About fire protection of heat insulation, heat dissipation and ceiling The following are some suggestions of the author.

(1) Protect the wire holes through the ceiling with fireproof rings, and wrap the wires at the holes with a fireproof package. In the first half of 2000, the short circuit of the Beijing Hualong Lamps Co., Ltd. ignited the wire insulation material, flames propagated upwards along the wire, passed through the wire through holes and gaps, and ignited into the ceiling, expanding the range of flame burning and destroying the light city. Once, the direct economic loss amounted to more than 20 million yuan;

(2) For the ceiling lamp box, the wall-mounted and concealed sockets, and the switch box are adhered to the inner surface of the box with a fireproof pad, which acts as a fire and heat insulation, and can prevent smoke and flame from knocking out of the box. Space, such as breaking into the upper part of the ceiling, can also suppress the internal fire and does not affect the beauty of the decoration environment;

(3) Protecting the downlights of the downlights, spotlights, and embedded fluorescent lamps can achieve the effect of heat insulation, ventilation, and heat dissipation. It can also use the effect of the fireproof coating on the overheating of the lamps and the arc sparks in the fire itself. Extinguish. Neon transformers installed in the ceiling can also be protected in this way. In hotels, restaurants, bars, karaoke rooms, theatres, factories and home constructions, embedded lighting facilities are becoming more and more popular, and their installation can endanger the fire resistance of the roof. According to the current situation of China's current research and production of fire retardant coatings, the technical conditions have matured and entered the international precedent. Domestic fireproof coatings can be used to produce a series of protective products for lamps and sockets to meet the needs of large quantities in the market. Although the unit price is not high, it needs a large quantity. To make the development product worthy of promotion, the product must be inexpensive and prevent the flame from spreading to the upper space of the ceiling. It does not affect the ventilation and heat dissipation of the lighting device, and does not reduce the separation of the ceiling. Heat and sound insulation effects are non-toxic and odorless environmental protection products. They can withstand the effects of cold, heat and ultraviolet rays. They have anti-mildew, anti-insect, anti-bacterial, and are not damaged by rodents and other parasites. They also have light weight and placement. Convenient, not maintenance and other characteristics.

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