Construction and installation technology of distribution box and switch box
1. Setting of distribution box and switch box
(1) The power distribution system is equipped with a general distribution box and a distribution box, and implements hierarchical power distribution.
(2) The switch box is distributed by the main distribution box.
(3) The horizontal distance between the switch box and the controlled fixed electrical equipment should not exceed 3M.
(4) There should be enough space and passages around the distribution box and switch box for two people to work at the same time, and no objects that hinder operation and maintenance should be stacked.
(5) The distribution box and switch box should be installed upright and firmly, and the mobile distribution box and switch box should be installed on a firm support. The bottom of fixed distribution box and switch box is larger than 1.3m and smaller than 1.5m.
(6) The switches and sockets in the distribution box should be firm and free from looseness or skewing.
(7) The working neutral wire and protective ground wire in the distribution box and switch box shall not be mixed.
(8) The connecting wires in the distribution box and switch box should adopt insulated wires, the joints should not be loose, and there should be no exposed live parts.
(9) The metal shell of the electrical box, the electrical shell and the electrical installation must be grounded. The protective neutral line should be connected through the terminal block.
(10) The distribution box and switch box must be rainproof, dustproof and anti-smashing.
2. Selection of electrical appliances
(1) The electrical appliances in the distribution box and switch box must be reliable and in good condition, and damaged or unqualified electrical appliances must not be used.
(2) The main distribution box shall be equipped with main automatic switch and shunt automatic switch, main fuse and shunt fuse, and leakage protector. The rated value and action setting value of the main switchgear shall be suitable for parallel switchgear.
(3) The main distribution box should be equipped with voltmeter, total ammeter, total watt-hour meter and other instruments.
(4) The distribution box should be equipped with automatic main switch and shunt automatic switch, main fuse and shunt fuse. The rated value and action setting value of the main switchgear shall be suitable for parallel switchgear.
(5) Each electrical equipment should have its own special switch box, and the system of "one machine, one gate" must be implemented. It is strictly forbidden to directly control two or more electrical equipment with the same switchgear.
(6) The switch cabinet in the switch box must be able to use electrical equipment for power isolation under any circumstances.
(7) A leakage protector must be installed in the switch box. The leakage protector is installed on the load side of the power isolating switch of the distribution box and the load side of the power isolating switch of the switch box.
(8) The selection of the leakage protector should meet the requirements of the national standard gb6829-86 "Leakage Action Protector (Leakage Action Protector)". The rated leakage current of the leakage protector in the switch box shall not exceed 30mA, and the rated leakage operation time shall be less than 0.1s.
(9) The rated leakage operating current and rated leakage operating time of the two-stage leakage protector in the main distribution box and switch box should be reasonably coordinated with hierarchical and segmented protection functions.
(10) The leakage protector must be installed and used according to the product manual. For the leakage protector that has been used for a long time and used continuously for one month, its characteristics should be carefully checked, and any problems should be repaired or replaced in time.
(11) Manual switch devices are only allowed to be used to directly control lighting circuits and power circuits with a capacity not greater than 5.5kW. The power circuit with a capacity greater than 5.5kW is controlled by an automatic switching device or a step-down starting device.
(12) The rated value of the switch should be applicable to the rated value of various equipment.
(13) It is forbidden to set the top and bottom of the box on the top and bottom of the box. The incoming and outgoing wires are bound with a sheath and made waterproof bends. The wiring harness must not directly touch the inlet and outlet of the box. The incoming and outgoing wires of the mobile distribution box and switch box must use rubber insulated cables.
(14) It is strictly forbidden to connect the power cord entering the switch box with a socket.
3. Use and maintenance
(1) All distribution boxes should be marked with their name, purpose and branch mark.
(2) All power distribution box doors are equipped with locks, and the power distribution boxes and switch boxes are in charge of special personnel.
(3) All distribution boxes and switch boxes are overhauled once a month. Maintenance personnel must be professional electricians. Wear insulating shoes, gloves, and use electrical insulating tools during maintenance.
(4) When the distribution box and switch box are overhauled, the corresponding power switch of the upper level must be disconnected, and the power failure sign must be hung. Live work is strictly prohibited.
(5) All distribution boxes and switch boxes must follow the following sequence of operations during use:
Power transmission operation sequence: main distribution box-distribution box-switch box,
Power-off operation sequence: switch box-distribution box-general distribution box
Electrical failure except for emergency measures.
(6) When the construction site is stopped for more than 1 hour, the power switch box should be cut off and locked.
