1. The power distribution system at the construction site shall be distributed in different levels. The main distribution box (or distribution room) shall be set up. The distribution box shall be set below the main distribution box, and the switch box shall be set below the distribution box, and the electrical equipment shall be set below the switch box.

2. The main distribution box shall be located in the area close to the power supply; the distribution box shall be installed in the area with relatively concentrated electrical equipment or load; the distance between the distribution box and the switch box shall not exceed 30m; the switch box shall be distributed by the final distribution box, and the horizontal distance between the switch box and the fixed electrical equipment controlled by it shall not exceed 3M

3. Distribution box and switch box shall be installed in ventilated, dry and normal temperature places. It is strictly prohibited to install it in the gas, flue gas, steam, liquid and other harmful media with serious damage, and in the places that are vulnerable to impact, vibration, liquid splashing and heat source baking; there should be enough space and channel for two people to work at the same time around the distribution box and the switch box, and it is not allowed to stack any items that hinder operation and maintenance, and there should be no weeds, shrubs, etc.

4. Distribution box and switch box shall be made of iron plate or high-quality insulating material, and the thickness of iron plate shall be greater than 1.5mm The electrical equipment in the distribution box shall be installed on the metal or non wood insulated electrical equipment mounting plate first, and then fastened in the distribution box as a whole; the metal plate and the distribution box shall be electrically connected.

5. The connecting lines in the distribution box and switch box shall be insulated wires, and the joints shall not be loose, and there shall be no exposed live parts; the working zero line in the distribution box and switch box shall be connected through the terminal board, which shall be set separately from the protective zero line terminal board; the metal box, metal electrical installation board of the distribution box and switch box, and the non live metal base and shell of the electrical appliances in the box shall be protected Protective neutral shall be connected through terminal block.

6. Power distribution box and lighting distribution box should be set separately. If they are combined in the same distribution box, power and lighting lines should be set separately.

7. The wire inlets and outlets in the distribution box and switch box shall be set at the lower bottom of the box. It is strictly prohibited to set them at the top, side, back or door of the box. The inlets and outlets shall be bundled with sheath and made with waterproof bends. The wire bundle shall not be in direct contact with the inlets and outlets of the box. The power lines entering the switch box shall not be connected with pins. The inlets and outlets of the mobile distribution box and switch box shall not be connected with pins Rubber insulated cable must be used for the mouth line and exit line.

8. The distribution box and switch box shall be installed firmly and correctly. The mobile distribution box and switch box shall be installed on the solid support. The vertical distance between the bottom surface of the fixed distribution box and switch box and the ground shall be greater than 1.3m , less than 1.5m The vertical distance between the bottom of mobile distribution box and switch box and the ground should be greater than 0.6m , less than 1.5m All distribution boxes and switch boxes must be rainproof Dust proof.