Introduction to Busway
Category: Power InfrastructureCommercial and industrial distribution systems use several methods to transport electrical energy. These methods may include, heavy conductors run in trays or conduit. Busway, a grounded metal enclosure containing factory-mounted bare or insulated conductors can be an effective method of distributing power. A bus bar is a conductor that serves as a common connection for two or more circuits. Standard bus bars in busway are commonly made of aluminum or copper.
A busway is used in numerous applications and can be found in industrial installations as well as high-rise buildings. Busway used in industrial locations can supply power to heavy equipment, lighting, and air conditioning. Busway risers (vertical busway) can be installed economically in a high-rise building where it can be used to distribute lighting and air conditioning loads. Busway provides flexible power distribution solutions for a variety of applications where change and adaptation are important.
NEMA Definition
National Electrical Manufacturers Association (NEMA) defines busway as a prefabricated electrical distribution system consisting of bus bars in a protective enclosure, including straight lengths, fittings, devices, and accessories. Busway includes bus bars, an insulating and/or support material, and housing.
A major advantage of a busway is the ease with which its sections are connected together. Electrical power can be supplied to any area of a building by connecting standard lengths of busway. It is typically faster to install or change than cable and conduit assemblies. The total distribution system frequently consists of a combination of busway, cable and conduit. In many cases busway can be used in lieu of the cable/conduit feeders at a lower cost.
Benefits of a Busway
If you need to add load to or extend power from an existing distribution system, a Busway systems may be the answer. First introduced in 1932, busway solved the automotive industry's need for a flexible power distribution system to serve its linear layouts. Since that time, this product has grown to serve many other types of loads.
Where and How to Apply Busway
You can install busway in most applications where you'd normally use cable and conduit. Busway manufacturers produce systems ranging from 100A to 6500A. Low-amperage applications include high-technology firms, such as computer manufacturers and test laboratories. The automotive industry and other heavy assembly industries require high-amperage busway systems.
Recognizing the need for flexibility, manufacturers developed elbows and offsets to make directional changes easy. With these fittings, busway offers extensive layout versatility. When new loads develop, it's easy to meet changing conditions by adding tap-off units and/or new sections. However, busway is not the best solution for every application. For example, if the situation requires low current to a specific source, you're better suited for cable and conduit, which is best for underground applications. Also, Sec. 364-4(b) of the National Electrical Code (NEC) says you cannot install busway where it's subject to severe physical damage or corrosive vapors.
Benefits to End Users
Busway provides an effective means of distributing power in a building. Since it requires easy maintenance procedures and is flexible, it's relatively simple for accommodating changing load situations. Maintenance primarily consists of annual inspection of joint fittings using an infrared heat gun, and then using a torque wrench to tighten appropriate connecting bolts. If required, it is possible to cut power to only a portion of a busway run so one can perform any required maintenance without risk of injury or equipment damage. |
