Overhead Busway I Open-Slot Power
Track Busway systems distribute electrical power through overhead busway runs installed above work areas.
This plug-in busway design allows tap-off boxes, power drops, and receptacles to connect directly into the open-slot busway and deliver flexible overhead power safely and efficiently to equipment below.
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Busway Plug-In Units and Power Drops Explained
Track Busway systems distribute electrical power through overhead busway runs installed above work areas. Plug-in units—often referred to as tap-off boxes or power drops—connect directly to the busway and allow power to be delivered safely and efficiently to equipment below.
Because these plug-in units can be repositioned anywhere along the busway, they provide a flexible alternative to traditional hard-wired power distribution systems.
What Is a Busway Tap-Off Box?
A busway tap-off box is a plug-in device that connects directly into the open-slot Track Busway and draws power from the internal conductors. These plug-in units allow equipment, lighting, and receptacles to connect anywhere along the busway run without installing additional conduit or wiring.
Depending on the application, power taps can be configured as outlet boxes mounted directly to the Track Busway or as breakered drop cord assemblies that bring protected branch circuits down to the workstation.
Open-Slot Busway Design
Track Busway uses a continuous open-slot design with insulated copper conductors housed inside a steel channel. This allows plug-in devices to access power anywhere along the run, rather than at fixed tap-off points.
Unlike conduit or fixed-window busway, open-slot access supports faster installation, easier expansion, and fewer homerun feeds — all while remaining code-compliant under UL 857 and NEC Article 368.
Busway Plug-In Units (Tap-Off Boxes)
The diagrams below illustrate how each pole configuration connects conductors and delivers voltage to the load.
1-Pole tap-offs connect one hot and the neutral to deliver 120V (line-to-neutral)
2-Pole tap-offs connect two hots (no neutral) to deliver 208V single-phase or 240V (line-to-line)
3-Pole tap-offs engage all three hots and the neutral to support 208V or 480V three-phase, four-wire configurations
Pole count refers to the internal breaker configuration of the plug-in unit, not the physical track.
For example, a 3-pole plug-in may be installed on a four-conductor (3-phase, L-L-L-N) Track Busway to serve three-phase loads with a neutral present.
Because these plug-in units deliver power directly from the overhead busway down to equipment below, many contractors refer to them as busway drop outlets or power drops.
Supplying Power Where You Need It
Track Busway provides suspended power distribution that delivers reliable electrical connections directly above the workspace. Because power is supplied overhead, equipment can be repositioned without cutting conduit or pulling new wiring.
By delivering power exactly where it is needed, Track Busway reduces floor congestion, long cord drops, and wall-mounted outlet limitations. This makes the system ideal for environments where layouts change frequently and power access must remain close to the point of use.
Busway Plug-In Unit Wiring Configurations
These diagrams show how Track Busway plug-in units connect to the internal conductors and deliver power to equipment below. Each configuration corresponds to a specific voltage and phase arrangement, allowing the system to support a wide range of applications.
Panelboard ‘A’ may be 120/208V or 277/480V depending on building service.
Available: 208/480V
Line to Neutral Available: 120/277V
Line to Line Available: 1Ph-208V or 1Ph-480V
Available: 208/480V
1-Pole, 2-Pole, and 3-Pole power taps on the 4-Pole (3-Phase Busway).
Standard Track Busway Configurations
Track Busway systems can be arranged in several overhead layouts depending on the workspace and equipment requirements. These configurations allow power to be distributed above work areas while maintaining flexible access for plug-in devices.
Choose the configuration that best matches your project layout:
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GRIDGRID configurations create evenly distributed overhead power across large areas. Ideal for facilities that require uniform coverage, GRIDs reduce homerun feeds and support flexible placement of power drops throughout the space.
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RECTANGLEsRECTANGLE layouts provide structured perimeter and interior coverage for defined work zones. This configuration is commonly used where power needs to be evenly distributed around equipment, benches, or production areas.
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ROWsROW configurations deliver linear overhead power directly above workstations or equipment lines. ROWs are ideal for targeted power distribution in manufacturing cells, labs, and retail environments.
