Bus duct is a closed metal device composed of copper and aluminum bus columns,used to distribute large power to various components of a distributed system.It has advantages such as structural features and adaptability.The outer shell of the bus duct is made of cold pressed track aluminum alloy profiles,which are easy to assemble and have a beautiful appearance.Adopting a separated air insulation type,the net distance between phases and between phases and ground is much greater than the standard requirements.The internal insulation components of the bus duct are made of high-strength epoxy resin material,which improves the resistance and thermal stability of the bus duct.The joint adopts a docking connection method and uses double connected copper bars,effectively increasing the contact area of the joint and making installation convenient and fast.

　　Compared with traditional power cable distribution methods,the use of dense bus ducts in distribution lines has many outstanding advantages.Such as small size,compact structure,and small space occupation;The transmission current is large,and the power branch line can be easily led out through the busbar slot plug-in switch box;Excellent material selection,high electrical and mechanical performance,and good grounding of the shell.Therefore,it is widely used in low-voltage distribution lines of high-rise civil buildings both domestically and internationally.Dense busbar trunking is not as flexible as air type busbar trunking with plug-in holes for branch circuits,but it has good fire resistance.

　　Bus ducts generally consist of starting bus ducts,straight through bus ducts(with and without sockets),L-shaped vertical(horizontal)bent bus bars,Z-shaped vertical(horizontal)offset bus bars,T-shaped vertical(horizontal)three-way bus bars,X-shaped vertical(horizontal)four-way bus bars,variable capacity bus ducts,expansion bus ducts,terminal heads,terminal junction boxes,plug-in boxes,related accessories and fastening devices of bus ducts.Bus ducts can be divided into three types according to insulation methods:air type plug-in bus ducts,dense insulation plug-in bus ducts,and high-strength plug-in bus ducts.According to its structure and purpose,it can be divided into dense insulation,air insulation,air additional insulation,fire-resistant,resin insulation,and sliding contact busbar trunking.

　　The laying of bus ducts must be measured on site,and the accuracy of the length of the installed cable ducts is required.The height of the plug-in switch box for bus ducts should also be determined according to the design.When the fire protection distribution line is concealed,it should be laid in a non combustible structure,and the thickness of the protective layer should not be less than 30mm.When using exposed laying,metal pipes or metal cable trays should be coated with fire-resistant paint for protection,as metal pipes and metal trays themselves do not have fire-resistant properties.When using cables with insulation and sheath made of non combustible materials,metal pipes and metal cable trays may not be used for protection in the vertical shaft.However,when the line passes through the vertical shaft floor,it must be protected by plate pipes and trays,and the gaps between the upper and lower ends of the pipes and slots should also be sealed and isolated.