Construction site general distribution according to three, so the electric box should also be graded settings, that is, under the total distribution box, set the distribution of electric boxes, distribution boxes below the switch box, switch box below is the power equipment. The multimedia distribution box is the central link between the power supply and the electrical equipment in the distribution system. It is the electrical device specially used to distribute the power, and the power distribution is carried out through the distribution box at all levels. The main distribution box controls the power distribution of the whole system, and the distribution box controls the distribution of each branch. Switch box is the end of the distribution system, and then down is the use of electrical equipment, each of the electricity equipment by their own special switch box control, the implementation of one machine one gate. No equipment shall be used in conjunction with a switch box to prevent misoperation, nor shall power and lighting control be placed in a switch box to prevent lighting from the power line failure. When the switch box is connected with the power supply, the electrical equipment is connected frequently. The operation is frequent and dangerous, and it must be paid attention to. The choice of electrical components in the distribution box must be in line with the wiring and electrical equipment. The electric box is installed vertically and firmly, leaving operating space around, no water on the ground, no debris, no heat source nearby, no vibration, the electric box should be rainproof and dustproof. The switch box shall be no more than 3m of the fixed equipment to be controlled.