Whether there is an external overhead line, understand the voltage level of the external line and the safe distance from the building, determine the position of the power transformer, the position of the power incoming line, and the position of the general distribution room
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2) The repetitive grounding electrode shall be made of Φ 50 * 4 steel pipe with a length of 2500mm, one or two of which shall be vertically driven into the ground with a spacing of 5000mm, and the welding shall meet the specification requirements.
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3) For tower crane, due to its arm length and rotary movement in use, direct lightning protection should be set under any circumstances
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03 design of grounding and lightning protection device 1) when the construction site and external power lines share the same power supply system, the grounding and neutral protection of electrical equipment shall be consistent with the original system
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4) Site survey is very important for the compilation of construction organization design, and it is the key to the compilation of temporary power consumption for construction
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6) If it is necessary to change the construction organization design of temporary electricity in the process of implementation, the approval procedures must be fulfilled, and the relevant calculation process and relevant drawings and data shall be supplemented
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2) When TN system is used as protective neutral connection, the working neutral line (N line) must pass through the main leakage protector, and the protective neutral line (PE line) must be led out from the repeated grounding point of the zero line of the power supply incoming line or the zero line of the power supply side of the main leakage protector to form a local TN-S neutral connection protection system
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It is not allowed to connect one part of equipment to neutral and the other part to ground
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2) If the temporary electrical equipment is less than 5 sets and the total capacity of the equipment is less than 50KW, the safe electricity use measures and electrical fire prevention measures shall be prepared
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This paper mainly includes the following parts: 1) the characteristics of construction site temporary electricity; 2) the main specifications and standards involved in temporary electricity; 3) temporary electricity Application scope and compilation requirements of construction organization design; 4) compilation content and steps of temporary power construction group: divided into nine parts
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Due to the long space, the power load calculation, transformer selection and distribution system design are in the first and second articles of this series, which can be read for reference
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4) The grounding and lightning protection of construction site are mainly repeated grounding and direct lightning protection
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Relevant drawings and data shall be supplemented when the design of power consumption organization is changed
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The construction site temporary electricity method detailed explanation Series 1, construction site temporary electricity load calculation detailed explanation, including example 2, site temporary power transformer capacity selection, distribution system design, cable selection and distribution box structure design
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This article is the third of the series of detailed explanation of temporary power use on construction site, and introduces the whole content of temporary power construction organization design in detail
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Its tower top and arm frame can be used as lightning arrester without additional lightning rod; its body can be used as down lead, and the grounding body can be repeatedly grounded with PE wire, and the grounding resistance is not more than 10 Ω
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The contents and steps of the temporary power construction group are as follows: 1) site investigation; 2) determination of power supply incoming line, substation or distribution room, distribution device, location of electrical equipment and route
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The characteristics of temporary electricity use in construction site are as follows: 1) temporary or temporary; 2) mobility and mobility; 3) open air; 4) main specifications and standards related to non selective temporary electricity use in geographical location and natural conditions; 1) technical code for safety of temporary electricity use in construction site (jgj46-2012; 2) management regulation for safety data of construction site of Construction Engineering (dbj11 / 383-2014; 3) building electrical engineering Code for acceptance of engineering construction quality (GB 50210-2011; 4) standard for safety protection, site sanitation, environmental protection and fire protection of construction site (dbj01-83-20035) national technical measures for design of civil building engineering electrical (2009 Edition); 6) code for design of low voltage power distribution (GB 50054-2011; 7) code for safety of power supply and consumption of construction site (GB 50194-2014; 8) ）”Standard for safety inspection of building construction” jgj59-2011 “scope of application and compilation requirements of temporary power construction organization design 1) temporary power construction organization design shall be prepared when the temporary power equipment is 5 or more or the total capacity of the equipment is 50KW or more
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3) When designing the route of the line, the overhead line should be set on one side of the road as far as possible, and the safe distance from other equipment should be considered at the same time
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5) Temporary power construction must draw temporary power engineering drawings separately, which can be used as the basis for the construction and application of temporary power engineering
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2) According to the number of new engineering units, mechanical equipment layout, processing workshop layout (steel processing, woodworking, etc.) in the general construction plan, the location of staff dormitory and office, determine the power supply circuit in the general distribution cabinet, the number of distribution boxes, switch boxes and mobile distribution boxes, and determine the number of distribution box circuits according to the equipment and lighting conditions
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4) The temporary power utilization project must be checked and accepted by the Department of compilation, examination and approval and the user, and can be put into use only after it is qualified
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Direct lightning protection 1) the main parts to be considered in the construction site are tower cranes, material hoists, external elevators and other large mechanical equipment, steel scaffolding, metal structures and other overhead facilities, and the lightning protection is classified into three types
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2) The average annual thunderstorm days in Beijing are 35.6 days
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Count and summarize the number and capacity of electrical mechanical equipment (pile foundation engineering can be considered according to the actual capacity of electrical equipment)
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(1) according to the actual situation of the power supply and the opinions of the local power supply department, determine the power supply incoming line path and line laying mode
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(this part is basically completed by the owner) 2) the main distribution box should be set close to the power supply, and the distribution box should be set in the place where the electrical equipment or load is relatively concentrated
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The scope of lightning protection can refer to Appendix B of JGJ46-2005
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3) it is strictly forbidden to install switches or fuses on PE line, to pass through the working current, and to break the line
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The distance between distribution box and switch box shall not exceed 30 meters
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Repeat grounding 1) in TN-S system, in addition to repeat grounding at the distribution room or main distribution box, repeat grounding must also be done at the middle and end of the distribution line
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It is also the key to ensure the safety and reliability of power consumption, meet the construction needs, reduce investment and repeat work, which must be attached great importance
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3) According to the general layout of the construction, the location of the general distribution room, distribution box, switch box and the cable route are preliminarily determined, and the cable laying mode (direct burial, cable trench, through protective pipe, etc.) is preliminarily determined according to the survey situation
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When the distance between the switch box and the distribution box is long, the repeated grounding device should be set
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In general, in the actual setting of the construction site, the main distribution box and distribution box should be set with repeated grounding device
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When burying underground, the underground situation should be considered, and the safety protection of crossing, entering underground and leading out from underground should be done well
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3) Load calculation (construction site temporary power load calculation details, including examples) 4) selection of transformer, design of distribution system (site temporary power transformer capacity selection, distribution system design, cable selection and distribution box structure design) 6) design of grounding and lightning protection device 7) drawing of electrical plan, elevation and system diagram 8) determination of protective measures 9) safe use of construction power Electrical technical measures and electrical fire prevention measures ﹣ 01 ﹣ site investigation ﹣ 1) according to the general layout, enter the construction site for exploration, understand the location of the building, the relationship between the project to be built and the built project, and map the terrain, whether there are water supply and drainage pipelines or other pipelines underground
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The mechanical equipment and elevated facilities with the height of more than 32 meters and beyond the lightning protection scope of adjacent buildings and structures should be equipped with lightning protection devices
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3) During the design and change of temporary power construction organization, the procedure of “preparation, review and approval” must be followed, which shall be prepared by electrical engineering technicians and implemented after being reviewed by relevant departments and approved by the technical director of the enterprise with legal personality
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