Electrical busway, also called bus duct or busduct, distributes power through copper or aluminum bars, called busbars, inside a protective housing. Factory-built sections join to carry power through a building.
How electrical busway works
Feed the runA feed connects the power source to the busbars.
Join and support the sectionsJoints carry power from one section to the next, and hangers support the row.
Connect the equipmentA tap-off, also called a bus plug, connects a machine or other equipment to compatible plug-in busway.
Main Types of Electrical Busway
Compare how each type delivers power and where equipment can connect.
| Busway type | How it distributes power | Key distinction |
|---|---|---|
| Feeder busway | Carries power between transformers, switchgear, or floors. | Used for the building’s main power routes. Any tap connections depend on the selected product. |
| Fixed-window plug-in busway | Serves loads along a run through factory-made plug-in openings. | Compatible tap-offs connect at the available fixed openings. |
| Track busway | Serves loads along a run through a continuous-access slot. | Position compatible tap-offs where equipment needs power along the accessible run, rather than being limited to fixed plug-in openings. |
Feeder busway
Common uses include connecting a transformer to switchgear or carrying power between floors. Check the selected product for available fittings and any permitted tap connections.
Fixed-window plug-in busway
Tap-offs connect at openings built into the housing. Check that those positions suit your equipment layout and that the system ratings meet your power needs. See the plug-in busway access comparison.
Track busway (continuous access)
If you expect to add a machine or move a workstation, a continuous slot lets you position a compatible tap-off where the equipment needs power along the existing run. Qualified personnel can reposition the tap-off at locations permitted by the system’s instructions.
See a PowerDrop connect to the busway
Watch a T225 tap-off being positioned and locked into the continuous slot.
These are common arrangements, not an exhaustive list. Specialized systems include trolley busway and medium-voltage bus duct.
Busway, Bus Duct, Busbar, and Conduit: What's the Difference?
Busway and bus duct commonly refer to the same general equipment category. The name alone does not tell you whether it uses fixed openings or continuous access. The table below explains how these terms relate.
| Term | What it describes | Key distinction |
|---|---|---|
| Busway | The assembled distribution system: enclosed busbars, joints, feeds, fittings, and supports. | A complete manufactured system. |
| Bus duct / busduct | A commonly used name for enclosed-busbar distribution equipment. | Feeder busway is one example. Bus duct can also have plug-in openings. |
| Busbar | A conductive bar, typically copper or aluminum, that carries current. | A component found inside busway, switchgear, and other equipment. |
| Conduit | A raceway—a protective path—for separately installed wires. | A wiring method using separately installed conductors. |
When Does Busway Make Sense Instead of Cable and Conduit?
Busway can consolidate a distribution route into factory-built sections. Cable and conduit offer a familiar way to route individual circuits. The better fit depends on loads, space, installation conditions, and future changes.
Conduit + wire
A new connection may need field work.
Red dashed = possible new conduit work
Continuous-access busway
A compatible tap-off can serve B here.
Solid red = access to plug-in power overhead
Gray = former B position
Consider busway when
- Several loads share a common distribution route.
- Modular sections simplify installation or future expansion.
- Plug-in access would reduce rework when equipment moves.
- A backbone route calls for a suitable feeder busway system.
Consider cable and conduit when
- Circuits and equipment locations are expected to stay fixed.
- The route requires extensive custom field routing.
- The available busway does not suit the environment or required ratings.
- The complete installed-cost comparison favors conventional wiring.
Busway is not automatically cheaper. Compare equipment, installation labor, supports, protective devices, downtime, and the likely cost of future changes.
See how busway moves power overhead
See how a T225 run brings power overhead, from the end feed and connected busway lengths to equipment tap-offs.
Where busway is used
Feeder busway can carry power between floors in a hospital or high-rise. These five guides show how plug-in track busway brings power to equipment along a row or across a work area.
Industrial Feed machines and packing stations as a line changes.
Automotive Bring power to service tools and vehicle test stations.
Laboratories Connect instruments as the equipment on a bench changes.
Commercial & Institutional Supply counters, displays and teaching stations.
Data Centers Add rack connections as a row grows.Busway Ratings and Selection Considerations
A busway's name or appearance is not enough to select it. Match the actual product documentation to the electrical design and installation environment.
- Voltage, current, and conductors: confirm voltage, phase, ampere rating, neutral and grounding arrangements, and calculated load.
- Fault current and protection: coordinate busway short-circuit ratings with available fault current and protective devices. Device interrupting ratings and busway withstand ratings describe different duties.
- Route and environment: check clearances, supports, joints, voltage drop, enclosure ratings, and indoor or outdoor suitability.
- Connection method: confirm tap-off locations, compatible devices, and the protection required for each load.
Standards and product listings
UL 857 covers busway and associated fittings. NEC Article 368 addresses busway installations. Apply the code edition adopted for the project and the instructions for the listed product.
Ratings vary by system; a voltage or ampere limit for one Track Busway product is not a limit for the entire busway category. See USA TrackBusway's listing and code information for our systems.
Common Questions About Electrical Busway
Is busway the same as bus duct?
The terms commonly overlap. Read the specification to identify the system's intended use, access method, construction, and ratings rather than assuming those features from its name.
What is compact or sandwich busway?
These terms describe construction with closely arranged conductors in a compact enclosure. Construction style and tap-off access are separate characteristics; check whether the selected product is feeder or plug-in.
Can track busway replace a high-amperage feeder?
They serve different distribution needs. A replacement requires an electrical design that satisfies all loads, ratings, protection, and routing requirements. A lower-rated track run is not a direct substitute for a higher-rated backbone feeder.
Is every busway suitable outdoors?
No. Confirm the specific product's enclosure rating, environmental suitability, and installation instructions. An indoor system should not be assumed suitable for moisture, dust, or outdoor exposure.
Need Flexible Power Along an Overhead Run?
Learn how continuous-access Track Busway delivers power to equipment and how its components fit together.
