Fire safety knowledge of lighting systems in large performance venues

The large-scale event stage and lighting system are usually temporary facilities with large power consumption. Many electrical wires are distributed in the audience and stage performance activity area, and meet with personnel, scenery, combustible decorations, etc., which increases the electrical fire risk of large-scale event places. Therefore, the electrical fire safety of the lighting system of large-scale activities has become an important part of the fire supervision of large-scale activities.

Characteristics of 1. lighting devices and technical measures for fire safety
Fire Safety of (I) Basic Light Source
The basic light source is mainly concentrated in the stage performance area. According to different positions and uses of the light, it can be divided into surface light, side light, top light, sky light, ground light and flowing light, etc. Generally, it is equipped with spotlight, floodlight, return light and chase light, etc., with power 0.5 kW to 2 kW. Because these lighting devices are lit when the temperature of the lamps is high, and with the stage curtain, scenery, sky curtain, side curtain and other decorative objects close to the distance, it is the focus of fire prevention, in the basic light source design, installation, should pay attention to the following points:
1. The lamp should be installed on a non-combustible base, and the distance between the curtain and other combustible textiles should be greater than 0.5 meters, and the distance between the front of the lamp should be greater than 1.5 meters. It should be fully estimated that the spacing is affected by factors such as curtain lifting, opening and closing, lamp movement and swing caused by natural airflow, and heat insulation measures should be taken if the safety spacing cannot be met. If the curtain is close to the column light, a fixed metal bracket or net cover should be set to block the curtain from being close to the lamp.
2. When there are people or flammable materials under the lamp, the front of the lamp and the heat dissipation hole shall be equipped with a lead wire protective net or a baffle made of non-combustible material to reduce the harm caused by glass fragments and hot filament splashing caused by the burst of the lamp.
3. For buildings such as old theaters with wooden structures, because the space of the light bridge is very narrow and the temperature is relatively high, problems are not easy to detect, and there must be no combustibles around the lighting equipment in such parts.
4. Avoid hanging flags, launching ribbons, releasing balloons and setting up other moving objects in the air in the lighting device area to prevent these items from directly contacting high-temperature lamps and causing fires caused by winding and collision.
5. The construction and hoisting of temporary light racks shall be approved by the building adjustment department in advance for the load capacity and installation method of the load-bearing components. The towering floor lamp frame shall have measures to prevent the center of gravity of the lamp frame from tilting to the side of the installation lamp and the side of the standing operator.
Outdoor large-scale event venues must fully estimate the safety factor and specific preventive measures of the lighting system under severe weather conditions. In outdoor, waterproof distribution box, connectors, lamps, etc. shall be generally selected, and other rainproof measures shall not affect the heat dissipation of electrical equipment.

Fire Safety Problems of (II) Art Effect Lamp
Art effect lights are commonly used in computer lights, neon lights, laser lights, fiber optic lighting, plastic rainbow lights and all kinds of mechanical rotating lights. When designing these lamps, the artistic effect and fire safety should be combined, and special attention should be paid to the safety of neon lights. The working voltage of neon tube, which is widely used in large-scale activities, is as high as 5000V, which is easy to produce electric spark and arc, and has great fire danger. Therefore, the lamp handle and base plate of neon lamp shall be made of non-combustible materials or treated with fire retardant technology for combustible materials; when the neon lamp transformer and lamp tube are installed in the parts that may be contacted by personnel, protective measures shall be taken. Neon lights hanging outdoors should prevent short circuits caused by shaking and collision. There is a forced air cooling device inside the computer lamp, the tuyere cannot be covered, and the fan failure is prevented. The laser lamp is cooled by circulating water, the installation of the water pipe should be reliable, and the water source should be avoided. The layout of the artistic effect lamp should also be considered not to affect the fire safety evacuation and not to occupy the fire passage.

Fire Safety of (III) Auxiliary Equipment

Auxiliary equipment is a device that matches the lighting effect, usually a smoke machine, a snowflake machine and a bubble machine. Smoke machine is a large amount of carbon dioxide gas generated after heating dry ice, which forms thick fog along the ground after being sprayed out. It is a high-power electric heating equipment with fire hazard. Poor contact of the power terminal of the equipment, exposed live terminals, and electrical damp short circuit are common problems. The smoke generated by the smoke machine does not settle on the ground but spreads everywhere, which will cause the fire detector alarm and the linkage of fire fighting equipment. Sometimes, the on-site personnel will be mistaken for the smoke generated by the fire, resulting in unnecessary panic. However, the smoke machine and bubble machine itself generally have no fire danger.
  
Common fire risk factors of (IV) lighting power line
At present, the commonly used domestic bakelite connector material quality is poor, the process level is low, the connection is easy to loosen, the contact resistance is large and overheating occurs. The connector is heated for a long time, which accelerates the aging of the insulating material, and then easily causes a short circuit. Due to the large load of the wires in the lighting system and the high heat generation, sometimes bundles of temporary wires are tied or stacked together, improper laying methods and poor heat dissipation conditions, resulting in further increase in the temperature of the wires. The denser the wire and the greater the current, the higher the calorific value. Temporary electrical circuits of the lighting system are easily damaged by mechanical external forces such as impact, abrasion and extrusion during the lifting, expansion and rotation of the stage and props, when crossing roads, stacking heavy objects, and when steel folding chairs are used, such as improper installation and setting of electrical wires, resulting in damage to the electrical insulation protective layer or contact of charged bodies with the shell, causing short circuit. Some installation and construction units do not work according to the specifications and try to save trouble by simply winding multiple power wires around electrical connection terminals or using unmatched connection terminals, resulting in poor contact at the connection. When large current passes through, the joint overheats and ignites combustible materials or electrical insulation.
  
Method of fire audit and inspection of 2. lighting system
(I) to determine the feasibility of lighting system scheme
It is necessary to understand the main content of the large-scale event, the venue arrangement, the basic situation of the building fire protection facilities, power supply and distribution, and electricity consumption of the event venue, and inquire about the habits and problems of holding large-scale events in the history of the venue. Secondly, review the lighting system layout, power supply system diagram, electrical equipment list and related technical issues. After discussion and modification of the scheme, a formal design and construction drawing of the lighting system will be formed.
On-site inspection of (II) lighting system
The inspection can be divided into two stages: one is the inspection in the installation and commissioning stage, which mainly checks whether the installation layout, selection, appearance quality and protective measures of the electrical circuit and lighting device of the lighting system are reasonable, and can test the power consumption of the local power distribution equipment. The second is the inspection in the trial operation stage of the system, that is, the inspection in the continuous rehearsal and rehearsal stages of large-scale activities. After the lighting system is fully put into use, the safety status of the system under the condition of long-term continuous operation is confirmed, and the hidden danger of electrical fire is eliminated.
(III) to strengthen the large-scale activities held before the place of electrical testing
The normal operation of electrical circuits, equipment, appliances, etc. in large-scale event venues will directly affect the fire safety of the venue. A little carelessness is prone to fire hazards such as high temperature of electrical appliances, aging circuits, open circuits, short circuits, overload, and equipment ignition. Improper control will lead to serious fires. Therefore, strengthen the inspection of electrical appliances before large-scale event venues, it can timely find out the improper installation and use of electrical equipment and lines, find out the operation of electrical equipment and equipment, abnormal quality, and the matching of rated voltage and current of power supply and distribution and the use of electrical equipment and appliances, so as to eliminate fire hazards in time.