A conversation on electrical bus duct is influenced and biased by the experience and expertise of the individuals There is service bus, feeder bus, and plug in bus duct. Service bus duct typically takes power from the main outdoor transformer to the main indoor switchboard. Feeder bus typically takes power from the main switchboard to another area of the facility. Plug-in bus duct distributes power in an area by allowing you to tap into the bus duct, using bus plugs that feed individual machines, motors, panels, disconnects, etc. In this discussion, we are mainly talking about plug-in bus duct and bus plugs. Do you want a centralized distribution system or a de-centralize system? An example of a centralized system would be a 1200 amp panel board with 12 molded case circuit breakers sized between 100 amps and 600 amps. Each circuit breaker powers a feeder to an individual machine, disconnect, motor, or sub panel. So there are 12 conduits coming out of the 1200 switchboard and going to 12 separate loads. A decentralized distribution system would be a 1200 amp bus duct going from the main 1200 amp switchboard, right through the middle of a production area, hanging from the trusses, and having 12 bus plugs attached to it. Each bus plug is used to feed 12 separate loads, such as a 225 amp panel, a 25 hp motor. 4 molding machines, a step down transformer, and four other production machines spread around the production area. Instead of 12 feeders from the main switchboard, there would be one bus duct and 12 short drops, i.e. feeders, from overhead bus plugs, attached to the bus duct.