What work is needed for the construction scheme, construction and price of the steel enclosure, and how many days does it take to complete the 200 meters?

Construction scheme of double-wall steel cofferdam.

catalogue

Chapter I Compilation Basis 3

Chapter II Project Overview 3

2. 1 project brief introduction 3

2.2 Engineering Features, Emphasis and Difficulties 4

Chapter III Construction Scheme of Double-wall Steel Cofferdam 4

3. 1 Construction Process of Double-wall Steel Cofferdam 4

3.2 Structural Design of Double-wall Steel Cofferdam 5

3.3 Preparation for Construction of Double-wall Steel Cofferdam 5

3.4 Assembly of Double-wall Steel Cofferdam 6

3.5 steel cofferdam sinking 7

3.6 Layout of Construction Platform and Conduit Figure 8

3.7 Concrete Back Cover 8

Chapter IV Calculation of Rectangular Double-walled Steel Cofferdam 9

Chapter V Quality Assurance System and Assurance Measures 9

5. 1 Overall quality objective 9

5.2 Quality Assurance System 9

5.3 Quality Assurance Measures 10

Chapter VI Safety Assurance System and Safety Assurance Measures 12

6. 1 safety target 12

6.2 Safety Assurance System 12

6.3 Safety measures 13

Attachment:

Attached Figure 1 Overall Layout of Double-wall Steel Cofferdams for Pier 5 and Pier 6 of Zhouhe Bridge

Attached Figure II Design of Double-wall Steel Cofferdams for Pier 5 and Pier 6 of Zhouhe Bridge

Appendix III Design and Calculation of Double-wall Steel Cofferdams for Pier 5 and Pier 6 of Zhouhe Bridge

Chapter II Project Overview

2. 1 Project Introduction

2. 1. 1 physical geography overview

This bridge is located in the valley area and is about 54 meters high. The bridge site is located on both sides of Zhangzhou River, with steep terrain and large river flow. The gully bed is soft soil, partially covered with silty clay, and the longitudinal slope of the gully bed is large.

2. 1.2 geological structure

(1), soft soil (): σ0=80kPa.

(2) Silty clay ():, σ0= 150kPa.

(3) Triassic pebble soil: σo=400kPa.

(4) Mudstone mixed with sandstone: σo=600kPa

2. 1.3 Hydrological data

XX runs all the year round, and the water quantity changes greatly with the seasons. The flood season is from July to September. The hydrological data are q1100 = 20200m/s, h1100 = 279.66m, V 1/65438+. XX has good water quality and no corrosiveness to masonry. The riverbed is affected by scouring and sand mining, and the terrain fluctuates greatly, so the construction is very difficult.

2.2 engineering characteristics, key points and difficulties

The main bridge has a large span, with the maximum span of128m; The suspension casting section is heavy and many, and it has to go through rainy season and flood season, so the construction period of this bridge is extremely tight and the task is very arduous. This project is very difficult.

① Most of the riverbed is exposed, and bedrock is exposed in some places, which brings great trouble to the construction of trestle, platform, steel cofferdam and steel casing.

(2) The main pier caps are all designed as large-volume low-pile caps, and the double-wall steel cofferdam cannot sink to the design position.

(3) Construction interference. This project crosses the Zhouhe River, so it cannot be suspended during the construction period. The exchange of personnel and materials between the two sides of the strait is difficult, the construction interference is great, and the safety problem is more prominent.

Chapter III Construction Scheme of Double-wall Steel Cofferdam

3. 1 construction technology of double-wall steel cofferdam

Measuring and positioning → assembling the first double-walled steel cofferdam → lowering the first double-walled steel cofferdam → welding and lowering the second and third steel cofferdams in turn → checking the elevation of the top surface of the steel cofferdams → positioning and fixing → divers checking the contact between the bottom of the box and the river bed → throwing sand bags according to the bottom-up situation → inserting concrete conduits to seal the bottom → pouring concrete for sealing the bottom → pumping and setting internal supports → leveling the base, plugging → construction of the pile caps and pier shafts.

3.2 Structural design of double-walled steel cofferdam

Each set of double-walled steel cofferdam is made in three sections, and each section is divided into eight pieces for processing. Each member consists of peripheral plate, inner wall plate, external stiffening plate, internal stiffening plate, connecting plate, internal support, internal inclined support, vertical stiffening rod, side foot stiffening rod, side foot stiffening plate, side foot sealing plate and side foot sealing bottom plate. See the material list for the specifications and weight of materials. The height of the first section is 4.8m, and the space inside the wall is 0.9m 19.7* 16m. See the figure for cofferdam compartment layout. Before making the steel cofferdam, make the double-walled steel cofferdam fixture as shown in the figure. After the double-wall steel cofferdam is processed in blocks, the semi-finished products should be inspected, including the structural size, weld quality, whether there are holes in the weld after the welding slag is removed, and kerosene should be applied to the weld to check whether there is water seepage on the back. After the completion of bored pile construction, 25t crane combined with floating crane is used to erect and assemble the stress joint at the bottom section, and 35# steel is used as the beam to connect the steel pipe pile with the steel casing firmly, and the corbel is welded to meet the requirements of assembling the steel cofferdam at the bottom section. Then mark the positioning line of the blade foot on the assembly platform, and the bottom section steel cofferdam can be assembled.

3.3 Preparation for Construction of Double-wall Steel Cofferdam

Before the construction of double-walled steel cofferdam, the preparation of personnel and machinery must be checked, and the whole platform must be inspected. If fatigue welding is found, it needs to be repaired in advance to ensure the smooth lowering of the steel cofferdam. Strengthen the dispatch of field equipment; According to the construction progress, even if the machinery is deployed, it will be used as it is, without wasting time.

For steel cofferdam construction, the staffing is as follows: commander 1, deputy commander 1, technical director 1, full-time dispatcher 1, 3 engineers and technicians, 3 construction operation guides and 30 construction teams. Construction personnel and technicians strictly follow the instructions to ensure the smooth progress of the construction. In the whole process of steel cofferdam construction, the mechanical conditions that our department plans to invest are as follows:

Serial number Machine name, specification, model, rated power (KW) or tonnage or capacity quantity (unit)

1 towed concrete pump HBT 80 80 m3/h 2

Two Dongfeng 8M3 4 concrete mixers

3 excavators Hitachi 320 2M3

4 floating crane QY25 25t 1

5 crane QY25 25T 2

6 High pressure water pump DAZ- 100 * 6 75kW4

8 air compressors 20KW 3 sets

9 Steel bar cutter hqj 10 1.5kw5

10 steel bar straightener TQ4- 14 5.5kw5

1 1 welder type 3000 8

13 loader 50 longgong 2

3.4 Assembly of double-wall steel cofferdam

The assembly sequence of steel cofferdam is carried out in blocks at one time. The installation of bottom steel cofferdam should strictly control its plane position, size and verticality deviation, and the steel cofferdam can be fixed and assembled only after it meets the requirements. The error shall meet the following requirements: the deviation of the measured plane size is less than1/500 of the length and width; The height difference between adjacent compartments and the top surface is less than 100 mm, so appropriate hoisting and floating crane equipment should be selected for assembly, as shown in the figure. When lifting, use four wire ropes, fix them on the crane body of the steel cofferdam, and fasten the wind rope. When assembling a piece, it is found that its plane position size and verticality are greater than the design position, so the piece should be adjusted to the design position as far as possible by using the chain jack to reduce the accumulated error when assembling the closed section. The welding between two steel cofferdams should be carried out on both sides, and measures should be taken to reduce the deformation of the panel during welding. For example, step-by-step symmetrical jump welding is carried out first, and then repair welding is carried out to full welding. After each assembled panel is fully welded, a connecting stiffener is welded every1.0m.. The sinking of the bottom steel cofferdam is realized by a suspension system consisting of steel liners and platform steel pipe piles. Five groups of 35# I-beams and beams are arranged on the steel casing and steel pipe piles. Consider calculating the dead weight of the first section as 5 1t, setting 8 lifting points on the longitudinal and transverse beams respectively, and using 8 20t chain-inverted chains, 4 for lifting and landing, and 4 for safety.

3.5 steel cofferdam sinking

First, the bottom of the steel cofferdam sinks. When the lifting point is installed vertically, eight chain chains will be lifted simultaneously. When the first steel cofferdam is hoisted to a distance of 0.5m from the stress point of the blade angle, the lower stress point will be removed. In order to safely sink 100%, first stop when the four symmetrical inverted chains drop by 0.5m, then the four symmetrical inverted chains drop by 0.5m and sink to the design elevation in turn. Then four lifting points are removed and four lifting points are reserved for the second welding. In the second quarter, welding procedure:

In the first part, symmetrical blocks, block 3- block 7, are welded. When welding to Block 4-Block 8, weld four lifting lugs and then fix them with four inverted chains. Remove the four inverted chains in the first section and weld 1-5 blocks. Considering the self-floating calculation in the first section, according to the site design, two more lifting points are set up. In order to ensure the safe movement of the steel cofferdam from left to right and from top to bottom, about 35 cubic meters of concrete was poured at the corners of the double-walled steel cofferdam. Connect block 2 and block 6. After the completion of the welding in the first section, conduct a watertight test to ensure no leakage, and then conduct the sinking in the second section. All the chains fall slowly at the same time. When sinking must be self-floating but not sinking, water shall be injected into the double-walled steel cofferdam to make it sink to the calculated elevation, so as to stabilize the shaking of the cofferdam.

Then install the third section, the third section welding procedure:

Before welding and assembly in the third quarter, strengthen the positioning guide frame and add a set of guide systems at the four corners of the casing. For example, after the symmetrical welding in the second quarter is completed, when the water injection sinks to 0.5m away from the riverbed, stop the water injection, and send divers to know the flatness of the corners and riverbed. Measuring the center line of pier with total station. According to the thin weathered layer of silt in Zhouhe river bed, if the height difference is large, sand and mud can be filled in the blade angle until the blade angle is flat, and then sink into place. Due to the thin silt in the main channel of Zhouhe Bridge, the double-walled steel cofferdam of the main pier enters the riverbed for 0.5-0.8m At present, the water flow speed is gentle. After the steel cofferdam is planted, it can be stabilized by wire rope anchorage in four directions. After the cofferdam is planted, the water injection will continue to sink. According to the actual situation, if it can't sink, send divers to check the basement at the corner of the double-walled steel cofferdam to see if there is any water leakage. If there is the possibility of sand turning in the double-walled steel cofferdam, fill it with flaky soil and clean the bottom of the cofferdam after confirming that there is no leakage.

Suck once with a mud suction machine until there is no mud. In order to strengthen water stop and prevent leakage, a certain amount of gravel is backfilled and the basement is compacted.

3.6 Construction platform and conduit arrangement

At the top of the steel cofferdam, I-beams are used to build a working platform for back sealing concrete, and underwater concrete back sealing conduits are arranged. According to the actual situation of the double-wall steel cofferdam of the main pier of Zhouhe Bridge, the inner rectangle size of the double-wall steel cofferdam is 17.7m× 14m, and the outer rectangle size is19.86m×16.16m, and the effective grouting radius of each conduit is tentatively set at r = 4. Back cover concrete pouring * * * Nine φ280mm concrete pouring conduits are set for underwater concrete construction; Eight of them are fixed, and 1 is mobile. The first batch volume of conduit storage hopper is 8m, and the conduit is suspended for 20cm. Arrangement of conduits between double walls: According to the wall thickness of the double-wall steel cofferdam of 0.9m, the outer length is divided into two equal parts, each section is 9.93m, and the outer width is divided into two equal parts, each section is 8.27m. * * * Eight conduits are arranged. Each conduit is poured symmetrically with concrete between the double walls of the steel cofferdam.

3.7 concrete back cover

The construction sequence of pouring underwater concrete should be as follows: first, pouring concrete between the double walls of the steel cofferdam, and after the concrete is finally set, forming a consolidated and stable double-walled steel cofferdam; Pouring back cover concrete in double-walled steel cofferdam. In the process of pouring, the conduit should be lifted slowly with the rise of the concrete surface, and the buried depth of the conduit should be adapted to the falling depth of the concrete in the conduit. In the process of pouring, attention should be paid to the pile height and diffusion of concrete, and the slump and the buried depth of the conduit should be adjusted correctly, so that each plate of concrete can form an appropriate pile height and a running water slope not steeper than 1: 5 after pouring, and the conduit should be strictly prevented from entering the water when being pulled out. The final pouring height of concrete surface should be not less than 150mm higher than the design value. After the strength of the concrete to be poured meets the design requirements, pump water to remove the loose layer on the surface.

Pouring sequence of underwater back cover concrete: When pouring concrete, it is impossible to chop balls at the same time, so the construction of chopping balls one by one is adopted. The pouring sequence is from low to high, and from the periphery to the middle at the same time, so as to avoid the base laitance from concentrating on the edge of the base. At the same time, stabilize the double-walled steel cofferdam to prevent it from sliding to the center of the river.

The concrete back sealing scheme is based on the method of first two sides and then the middle. Two conduit points are arranged at the upstream and downstream positions in the steel cofferdam. After opening, the first batch of materials are sealed, and then concrete is poured continuously. The ninth conduit is used as the flow conduit. Most of the back cover concrete is completed by the first eight conduits, and the ninth conduit will be used in the later period of back cover. At present, some positions of the back cover of the two conduits cannot be taken into account, so the ninth conduit is used for underwater concrete pouring.

In order to make the underwater back cover concrete have good fluidity, the slump of concrete should be controlled at 18~20cm, and the sand ratio of the first batch of concrete should generally be controlled at 45%~48%. When sealing back concrete, consider using concrete pump truck to supply materials, so as to switch between the supply and each conduit point. In the process of concrete back cover, it is necessary to measure more points and master the flow direction and elevation of back cover concrete at any time. After the first batch of concrete starts, it needs continuous operation in one go.

During pouring, the concrete surface of the basement shall be inspected in real time according to the arranged measuring points to ensure the flatness of the concrete surface of the basement. After the bottom sealing of underwater concrete is completed, it is difficult to keep the top elevation consistent, and the top elevation should be controlled within the range of+10cm to -20cm.

Chapter IV Calculation of Rectangular Double-wall Steel Cofferdam

For the calculation of double-walled steel cofferdam, please refer to the calculation of rectangular double-walled steel cofferdam in appendix.

Chapter V Quality Assurance System and Measures

5. 1 Overall quality objectives

Ensure that all projects meet the current engineering quality acceptance standards of the state and the Ministry of Railways, and the first-time acceptance rate of projects reaches 100%.

The construction site shall be clean and tidy, and environmental protection measures shall be implemented to achieve civilized construction.

5.2 Quality Assurance System

5.3 Quality assurance measures

5.3. 1 organizational guarantee measures

Establish a quality management organization with the project manager as the team leader, with the project chief engineer and deputy project manager as the deputy team leader.

5.3.2 Ideological guarantee measures

Engineering quality is the final result of construction activities, which depends on process quality, and working quality is the guarantee and foundation of process quality and engineering quality. Engineering quality is a systematic project, with leadership as the key, system as the means and technology as the guarantee. After the construction team enters the site, quality education will be conducted in different projects and procedures, with a clear purpose, so that everyone can understand the quality requirements and standards.

Implement the leadership control, achieve civilized construction, and implement the idea of "quality first for a hundred years" in the actions of every construction worker who participates in the war.

5.3.3 System guarantee measures

5.3.3. 1 quality responsibility system

In order to ensure the construction quality, establish the project quality responsibility system step by step from top to bottom, sign the quality responsibility book, clarify the quality responsibility and obligation of the post, establish a perfect quality responsibility system, and ensure the construction quality to be effectively controlled.

5.3.3.2 quality one-vote veto system

During the whole process of project construction, the quality one-vote veto system is implemented, and technicians with qualifications and railway construction experience are appointed as quality inspection engineers and inspectors to be responsible for internal quality inspection, and the quality engineer is given one-vote veto. All materials, semi-finished products and finished products entering the site must be approved by the quality inspection engineer before they can be used in the project. The project inspection must be signed by the quality inspection engineer, and all projects requiring the signature of the supervisor must be reported after the quality inspection engineer has passed the inspection. Quality inspection engineers and inspectors shall exercise one-vote veto according to construction specifications and engineering quality acceptance standards.

5.3.3.3 technical disclosure system

Before each subdivisional work starts, the competent engineer shall make technical disclosure to all construction personnel on the basis of being familiar with the design drawings and specifications, explaining the design requirements, technical standards, functions and functions of the project, the relationship with other subdivisional work, construction methods, techniques and matters needing attention, etc. , and ask all personnel to clarify the standards so that everyone can know fairly well.

5.3.3.4 investigation and review system

The survey data must be rechecked by changing hands, and then submitted to the supervision engineer for approval before it can be used for construction. Establish the system of periodic retest of center line piles and leveling points, and establish the contact system between measurement and construction. The data of monitoring and measurement should be fed back to the construction scheme in time, and the construction method should be adjusted in time according to the feedback information to ensure the construction quality.

5.3.3.5's "Three Inspections" System

Adhere to the system of "self-inspection, mutual inspection and handover inspection" during construction. If the previous working procedure is unqualified, it is not allowed to enter the next working procedure. Adhere to the previous working procedure and provide quality assurance for the next working procedure. Sign management should be carried out on the process construction site, indicating the responsible person, operation content and quality requirements. , should be verified before operation and strictly monitored during operation.

5.3.3.6 Quality Responsibility Investigation System

Strengthen the management of the construction site, establish the accountability system for quality responsibility, define the division of labor, assign responsibilities to people, and clearly define rewards and punishments, so as to highlight key points, implement them in batches, standardize the construction, and pay attention to actual results. All quality responsibility certificates shall be signed, and the lifelong responsibility system for quality shall be implemented according to the rules and regulations of the unit and relevant laws and regulations.

Chapter VI Safety Assurance System and Safety Assurance Measures

6. 1 security objectives

Adhere to the policy of "safety first, prevention first", establish and improve the safety organization, improve the safety production guarantee system, put an end to particularly serious, serious and extraordinarily serious accidents, put an end to fatal accidents and prevent the occurrence of general accidents. Put an end to all liability accidents and ensure that people's lives and property are not damaged. Create a security standard site.

6.2 Safety guarantee system

Responsibilities of safety management agencies and safety personnel

In order to strengthen safety leadership and implement systematic and networked management, the project department set up a safety leading group with the project manager as the team leader and the safety director, deputy project manager and chief engineer as the deputy team leader; The operation layer is the safety engineer and the safety officers of each team; The executive layer consists of relevant departments and construction teams.

6.2. 1.2 security personnel allocation

The safety and quality department of the project department is equipped with 1 minister, 1 full-time safety inspection engineer. Each construction team is equipped with 1 full-time safety officer, and each team is equipped with 1 part-time safety officer, who are all responsible for safety work.

6.3 Safety measures

6.3. 1 Safety management measures

6.3. 1. 1 safety management system

All applicable local and project safety laws and regulations must be observed, preventive measures should be taken to eliminate potential safety hazards on site, and all personnel on site should be responsible for safety, and fences, lighting, safety and guards should be provided before completion and handover. Provide any temporary works (including roads, sidewalks, fences, etc.). Due to the implementation of the project, it may be necessary to use and protect the public and the owners and occupiers of adjacent land.

During the construction, we should adhere to the safety activity day study system and the safety regular meeting system, establish the approval system before the implementation of safety measures, establish the safety inspection system, establish the "three jobs" system and the "three assignments" system per shift, and establish the accident file system. Formulate special safety rules for aerial work, safety rules and regulations for excavation and blasting, operating rules and regulations for all kinds of mechanical and electrical equipment, safety instructions for electricity consumption and electric power erection and maintenance operation system, special safety rules for flood control and fire prevention, and special safety rules for emergency treatment. , so as to ensure that all work has rules to follow.

6.3. 1.2 safety education

Organize on-site personnel to seriously study safety laws, regulations, methods and systems such as "Safety Production Law" and "Technical Regulations on Railway Construction Safety", and educate all on-site employees on the sense of ownership, safety first, basic knowledge and skills of post safety, operating procedures, eliminating dangers and emergency measures, and observing rules and regulations and post operating norms.

When new workers take up their posts, they must go through three levels of education: management department, construction team and team. When workers change jobs, they must carry out safety technology education in the new job, so that each worker can master the operation skills of this job and be familiar with the safety technology operation procedures.

Educate the personnel engaged in blasting, welding, electrical, aerial, lifting, pressure vessel and other operations, all kinds of mechanical operators and motor vehicle drivers on safety production knowledge, and only after passing professional training and examination can they work at their posts.

6.3. 1.7 safety inspection

Establish a safety production inspection system, so that the team will conduct daily inspection and weekly summary, and the project department will conduct safety education and inspection and appraisal once a month, so as to keep the alarm ringing and make unremitting efforts.

6.3.2 Technical measures for safety assurance

6.3.2. 1 technical measures for safety in construction site

Taking the construction safety standard site as the carrier, strengthen the operation control on the construction site. Each construction team formulates its own construction safety standards according to its own construction content.

On-site safety management is mainly aimed at construction crossover operation, initiating explosive device management, blasting operation, transportation, beam transportation, safe electricity use and fire safety. And in accordance with the relevant technical safety rules of railway construction. In the process of transportation, arrange the walking route between the car and the construction personnel to prevent the construction personnel from colliding with various construction vehicles, causing casualties.

The site is flat and the drainage is always smooth. All kinds of roads on the construction site are smooth, solid and smooth, with lighting facilities. Set up safety warning signs on the construction site and set up safety production bulletin boards. Set up "five signs and one map" in key workplaces, dangerous areas and main passages, namely: engineering bulletin board, safety production record board, fire prevention bulletin board, safety accident-free record board, famous brand of main site management personnel and general construction plan. Safety signs should be set on site. Signs such as "Danger", "No Traffic" and "No Fireworks" must be hung in dangerous areas, and red light warning should be set up at night.

There are enough fire-fighting water sources and fire-fighting facilities in the on-site production and living quarters, and the fire-fighting equipment is managed by special personnel, and it is not allowed to be placed in disorder. Each construction work area consists of a volunteer fire brigade of 15 ~ 20 people, and all construction personnel should be familiar with and master the performance and usage of fire fighting equipment.

The safe distance of all kinds of houses, sheds, yards, etc. shall comply with relevant regulations, and the combustible materials on the site shall be cleaned at any time. It is strictly prohibited to pile up inflammable and explosive articles in and near places with kindling.

Management Measures for Safe Operation on Water in 6.3.2.2

(1) At the initial stage of construction, learn about the waterway conditions and navigation requirements from the port supervisor and waterway department, and then refine the construction plan. Before temporarily blocking the waterway, you must go through the relevant formalities at the waterway department in advance, set up protective measures in strict accordance with the requirements at the construction site, and set up protective boats to divert upstream and downstream traffic.

② The construction of temporary wharves, trestles and water platforms shall strictly abide by the regulations of the waterway department, and shall not destroy the river bank or occupy the waterway. And has a certain anti-collision ability.

(3) Negotiate with the waterway department, set aside special construction waters and set up navigation marks to guide ships to pass through the waters safely. It is forbidden for construction ships and machinery to invade the waterway.

④ Actively cooperate with the daily inspection and guidance of the waterway department and the harbor supervisor. Floating cranes and ships working on water must have good performance and comply with the relevant regulations of the navigation department.

Other safety measures

6.3.3. 1. Measures for safe use of electricity

Strengthen on-site electricity management. In accordance with the relevant provisions, set up production and living power lines, substations and transformer distribution cabinets. Electricians are composed of personnel who have received professional training, obtained employment certificates and have rich experience in power management. Set up power failure, fire extinguishing devices and fire fighting equipment. Working under high-voltage lines or stacking materials, erecting temporary facilities, parking machinery and equipment, and hoisting operations are all carried out in strict accordance with the specified height and scope. It is forbidden to pull wires and connect electrical equipment without permission, and non-professional electricians are not allowed to engage in electrician operations.

All local lighting on all kinds of machine tools and metal equipment adopts safe voltage of 36V and below. When working in metal container and humid environment, the voltage of the traveling lamp shall not exceed 12V. Safe voltage uses a double-coil transformer for power supply, and the hand-held traveling lamp has a well-insulated handle and protective cover. Electricians, welders, etc. Should hold relevant certificates, standardized operation. Don't work with electricity. Welders must wear protective masks and special gloves when working.

Temporary power consumption shall conform to the safety operation rules for power supply, and shall be inspected and protected regularly. Unqualified electrical equipment and lines should be replaced in time, and it is forbidden to run or operate in spite of illness. During the erection of construction power lines, safety control will be carried out from the following aspects:

Branch line erection: the branch line shall adopt wires with good insulation and no aging, damage and leakage; The poles are placed overhead and fixed with insulators. Hard sheathed tubes can be used for aisle wires and signs. The outdoor branch line adopts rubber wire overhead, and the joint is not subject to tension, which meets the insulation requirements. The cables in the distribution box are sheathed, so the wires are not messy. A drip bend is added to the upper line of the large-capacity distribution box.

On-site lighting: 220V voltage is used in general places. Lighting wires are fixed with insulators. It is forbidden to use flower thread or plastic thread. Wires must not be dragged anywhere or tied to scaffolding. The metal shell of the lighting lamp is grounded or connected to zero. The lighting switch box in the single-phase circuit is equipped with a leakage protector. Outdoor lighting lamps and lanterns from the ground not less than 3 m; Indoor distance from the ground is not less than 2.4m

Overhead lines: Overhead lines are set on special poles, and it is forbidden to be erected on trees or scaffolding. Overhead lines are equipped with cross arms and insulators, and their specifications, distance between lines and span.