Bus Duct - All The Basics Explained
What is the use of Bus Ducts?
A bus duct, also known as a busway, is a type of electrical distribution system that is used to transfer power from a source to multiple loads. It consists of a metal enclosure containing one or more conductors, which are typically made of copper or aluminum. Bus ducts are commonly used in industrial and commercial buildings, as well as in power generation and substation applications.

The main advantage of using a bus duct system is that it allows for a more efficient and reliable method of power distribution. It eliminates the need for individual conductor runs and reduces the potential for loose connections or other types of electrical faults. Additionally, bus ducts are relatively easy to install, maintain and upgrade, which makes them a cost-effective solution for many applications.
Bus duct may also be used to pass medium voltage wires over buildings , water towers and other structures, (mainly to give easy access for maintenance).
Type of Bus Ducts
- Rigid bus duct: This type of bus duct is made of metal and has a rigid structure. It is commonly used in industrial and commercial buildings and is known for its durability and longevity.
- Flexible bus duct: This type of bus duct is made of a flexible material and can be bent or shaped to fit into tight spaces. It is commonly used in situations where the bus duct needs to be routed around obstacles or through tight spaces.
- Plug-in bus duct: This type of bus duct is designed to allow for easy maintenance and upgrades. It features removable sections that can be easily replaced or added to as needed.
- Segregated phase bus duct: This type of bus duct is used to transfer power between different phases, it's also known as multi-phase bus duct.
- Insulated bus duct: This type of bus duct is used to transfer power in an electrical substation or other high-voltage application, where the insulation is needed to prevent electrical arcing or failure.
- Non-Segregated phase bus duct: This type of bus duct is used to transfer power between same phases, it's also known as single-phase bus duct.
The type of bus duct that is used will depend on the specific application, environmental conditions, and the level of power that needs to be distributed.
Technical Explanation of Bus Duct

In the above picture, a segregated phase bus system is displayed. This type of bus duct separates each phase of the electrical power distribution into its own metallic enclosure with a barrier between them.
This barrier provides a magnetic shield and isolates each phase from each other, similar to an isolated phase bus system (IPB). The metallic barriers also act as Faraday cages to balance the fields produced by the conductors inside the enclosure. This type of bus duct is designed to prevent short-circuits and reduce the effect of one phase on the other by arresting the magnetic field.
It operates like an enclosure with an interleaving arrangement, which balances the fields to a great extent and allows only a moderate field in the space. The enclosure can be made of MS or aluminum and the barriers are also made of the same metal. This type of bus duct is typically used in high voltage systems 3.3-11 kV and current ratings above 3000 A and up to 6000 A. Only aluminum enclosures should be preferred to minimize losses and enclosure heating.
Where is Bus Duct used?
