In the power transformation and distribution equipment, the bus is the conductor of confluence and current distribution, so the bus is also called bus bar.

According to the material, there are three kinds of busbars: copper, aluminum and steel. From the point of view of electrical conductivity, atmospheric resistance and chemical erosion function, copper is better, but the price of copper is more expensive, and generally less used except for other needs. The conductivity of aluminum is inferior to copper, but its price is low, so it is widely used. Although the price of steel is also low, its mechanical strength is high, but its resistivity is large, and it is also a magnetic material. When the AC current passes through, the eddy current loss, power loss and voltage drop are large. Therefore, it is not suitable to transmit large current, and it is generally only used as the bus connecting to neutral and grounding.

The electrical box shall be made of non combustible materials; open type distribution board can be installed in production places and offices with low risk of electric shock; closed box and cabinet shall be installed in processing workshop, casting, forging, heat treatment, boiler room, carpentry room and other places with high risk of electric shock or poor working environment; in hazardous workplaces with conductive dust or flammable and explosive gases. Sealed or explosion-proof electrical facilities shall be installed; all electrical components, instruments, switches and lines shall be arranged in order and easy to operate.

The bottom surface of the board (box) installed on the ground shall be 5 ~ 10 mm higher than the ground; the height of the operating handle is generally 1.2 ~ 1.5 m; there is no obstacle within the range of 0.8 ~ 1.2 m in front of the board (box); the protective wire shall be reliably connected; there shall be no naked charged body exposed outside the board (box); the electrical components to be installed on the external surface of the board (box) or on the distribution board shall be provided with screen protection.