The connection of the protection neutral line shall adopt the twisted connection mode (error) IV
.
3
.
When the minimum safe distance between protective facilities and external power lines cannot meet the provisions in the table below, measures such as power outage, relocation of external power lines or change of project location must be taken in consultation with relevant departments
.
It is strictly prohibited to mix PE line with N line, and PE line shall not be broken
.
It is forbidden to install switches or fuses on PE lines
.
The uncharged exposed conductive parts such as the metal box of distribution box, the metal shell and support of construction machinery, lighting appliances and electrical devices shall be connected to neutral protection, and the connection with the protective zero line shall be connected with copper nose
.
Power distribution box and lighting distribution box, power switch box and lighting switch box shall be set respectively
.
5
.
When hoisting near the external power overhead line, the minimum safety distance between any part of the crane or the edge of the object to be lifted and the overhead line edge at the maximum deflection shall comply with the following table: 5
.
The minimum safe operation distance shall comply with the provisions in the following table: 3
.
When the requirements of the above safety distance cannot be met, the external power line protection scheme must be prepared, insulation isolation protection measures must be taken, and eye-catching warning signs shall be hung
.
The distribution system shall be equipped with distribution cabinet or general distribution box, distribution box and switch box, and three-level distribution shall be implemented, Leakage protectors shall be installed in distribution boxes at all levels
.
It is not allowed to make protective neutral connection for some equipment and protective grounding for other equipment
.
Overhead laying of single insulated conductor shall not be adopted
.
In case of change of temporary power construction organization design, it shall be approved according to the original procedure
.
Aluminum conductor shall not be used as grounding body or underground grounding wire
.
8
.
The distribution box and switch box shall be finalized products produced by professional manufacturers and shall meet the requirements of low voltage switchgear and control equipment – Part 4: special requirements for building site complete equipment (ACS) (gb7251.4), technical code for safety of temporary electricity on construction site (jgj46) and standard for safety inspection of building construction (jgj59), And obtain the “3C” certification
.
The crane is strictly prohibited from crossing the external power overhead line without protective facilities
.
Sundries are stacked in front of the distribution box (error)
.
Safety technical archives must be established for temporary power use on the construction site
.
When there are 5 or more temporary electrical equipment on the construction site or the total capacity of the equipment is 50KW or more, the temporary electrical construction organization design shall be prepared
.
The insulation color of PE line is green / yellow
.
The grounding wire of each grounding device shall adopt two or more conductors and be electrically connected with the grounding body at different points
.
Construction in progress shall not construct, erect operation shed, build living facilities or stack components, racks, materials and other sundries directly under the external power overhead line
.
2
.
2
.
In addition to repeated grounding at the distribution room or general distribution box, the protective zero line in TN system must also be repeatedly grounded at the middle and end of the distribution system
.
Periodic inspection record Leakage protector tester grounding resistance tester II
.
Outdoor distribution lines shall be laid with cables
.
3、 Grounding and neutral protection system 1
.
9
.
Each electric equipment must have its own special switch box
.
3
.
When the power incoming line is three-phase and five wire, the wiring in the general distribution box (when the box type transformer is connected) when the power incoming line is three-phase and four wire, the wiring in the general distribution box (when the transformer is connected) 3
.
When the material of PE line is the same as that of phase line and working zero line (N line), its minimum section shall comply with the provisions in the following table
.
When the construction site shares the same power supply system with external power lines, the grounding and neutral protection of electrical equipment shall be consistent with the existing system
.
6
.
2
.
In TN system, the grounding resistance of each repeated grounding device of protective zero line shall not be greater than 10 Ω
.
The temporary power works shall be inspected regularly according to the divisional and subdivisional works
.
The erection of temporary facilities on site and the installation position of building hoisting machinery shall avoid the side with external power lines
.
During the inspection, the grounding resistance value and insulation resistance value shall be rechecked
.
It is strictly prohibited to use the same switch box to directly control 2 or more electric equipment.
.
The protective facilities shall be firm and stable, the protective barrier shall be set up with insulating materials, and the isolation protection of external power lines shall reach IP30 level (to prevent the intrusion of 2.5mm solid)
4
.
The electrical components such as disconnectors, leakage protectors and insulated conductors used in the distribution box must also obtain the “3C” certification
.
When erecting protective facilities, it must be approved by relevant departments, adopt temporary power failure or other reliable safety technical measures, and be supervised by electrical engineering technicians and full-time safety personnel
.
In the power system where the working grounding resistance is allowed to reach 10 Ω, the equivalent resistance of all repeated grounding shall not be greater than 10 Ω
.
The potential safety hazards found must be handled in time, and the review and acceptance procedures shall be performed
.
In TN-S neutral protection system powered by special transformer on the construction site, the metal shell of electrical equipment must be connected with special protection zero line
.
The protective zero line shall be led out from the working grounding wire, the zero line at the power side of the distribution room (general distribution box) or the zero line at the power side of the general leakage protector
.
Natural grounding body can be used for grounding, which should be connected with the foundation grounding grid of the project under construction to ensure its electrical connection and thermal stability
.
The door of the construction machinery protection neutral distribution box shall be used as the protection neutral, the overhead cable shall be hung with steel cable and support, and the overhead line support shall be used as the connection node of the protection neutral line
.
6
.
Repeated grounding device 1 (using natural grounding body) repeated grounding device 2 (using artificial grounding body) 4
.
The temporary power construction organization design shall be organized and prepared by electrical engineering technicians and can be implemented only after being approved by the technical director of the enterprise and the chief supervision engineer of the project
.
When the motor vehicle lane on the construction site crosses the external power overhead line, the minimum vertical distance between the lowest point of the overhead line and the road surface shall comply with the provisions in the following table: 4
.
1、 General provisions 1
.
7
.
2
.
5
.
Safety technical archives shall include the following contents: (1) all data of power consumption organization design; (2) modify the data of power consumption organization design; (3) technical disclosure data of power utilization; (4) inspection and acceptance form of power engineering; (5) test and inspection vouchers and commissioning records of electrical equipment; (6) measurement record of grounding resistance, insulation resistance and leakage action parameters of leakage protector; (7) regularly check (recheck) the table; (8) electrician installation, patrol inspection, maintenance and demolition records
.
Angle steel, steel pipe or smooth round steel shall be used for vertical grounding body, and threaded steel shall not be used
.
distribution box, switch box 1
.
Construction without the above measures is strictly prohibited
.
There is enough operating space in front of the distribution box (with protection around)
.
The setting of distribution box and switch box shall meet the following requirements: ⑴ Several distribution boxes can be set below the main distribution box; Several switch boxes can be set below the distribution box; Schematic diagram of three-level distribution and three-level protection (2) the main distribution box shall be located in the area close to the power supply, and the distribution box shall be located in the area where the electrical equipment or load are relatively concentrated; (3) the distance between the distribution box and the switch box shall not exceed 30m, and the horizontal distance between the switch box and the fixed electrical equipment controlled by it shall not exceed 3M; The distance between the distribution box, switch box and mechanical equipment and the switch box shall be centralized (wrong) ⑷ there shall be enough space and channel for two people to work at the same time around the distribution box and switch box, and no articles hindering operation and maintenance, shrubs and weeds shall be stacked
.
When TN system is used as protective zero connection, the working zero line (N line) must pass through the general leakage protector, and the protective zero line (PE line) must be led out from the repeated grounding of the incoming zero line of the power supply or the zero line on the power side of the general leakage protector to form a local TN-S zero connection protection system
.
A safe operating distance must be maintained between the outer edge of the project under construction (including scaffolding) and the external power overhead line
.
The upper and lower ramps of the scaffold shall not be erected on the side with external power lines
.
External power protection 1
.
External power protection measures 7
.
